Optical System, Exposure System, and Exposure Method

ABSTRACT

An optical system is able to achieve a substantially azimuthal polarization state in a lens aperture while suppressing loss of light quantity, based on a simple configuration. The optical system of the present invention is provided with a birefringent element for achieving a substantially circumferential distribution or a substantially radial distribution as a fast axis distribution in a lens aperture, and an optical rotator located behind the birefringent element and adapted to rotate a polarization state in the lens aperture. The birefringent element has an optically transparent member which is made of a uniaxial crystal material and a crystallographic axis of which is arranged substantially in parallel with an optical axis of the optical system. A light beam of substantially spherical waves in a substantially circular polarization state is incident to the optically transparent member.

TECHNICAL FIELD

The present invention relates to an optical system, exposure apparatus,and exposure method and, more particularly, to an exposure apparatus forfabricating micro devices, such as semiconductor elements, image pickupdevices, liquid-crystal display devices, and thin-film magnetic heads,by lithography.

BACKGROUND ART

In the typical exposure apparatus of this type, a light beam emittedfrom a light source is guided through a fly's eye lens as an opticalintegrator to form a secondary light source as a substantive surfaceilluminant consisting of a lot of light sources. A light beam from thesecondary light source is guided through an aperture stop disposed inthe vicinity of the rear focal plane of the fly's eye lens, to belimited, and then is incident to a condenser lens.

The light beam condensed by the condenser lens illuminates a mask with apredetermined pattern therein, in a superposed manner. Light transmittedby the pattern of the mask travels through a projection optical systemto be focused on a wafer. In this manner the mask pattern is projected(or transferred) onto the wafer to effect exposure thereof. The patternformed in the mask is of high integration and a high-contrast patternimage must be formed on the wafer in order to accurately transfer themicroscopic pattern onto the wafer.

There is thus the proposed technology of obtaining the high-contrastimage of the microscopic pattern on the wafer, for example, by setting apolarization state of exposure light to linear polarization ofcircumferential vibration (hereinafter referred to as “azimuthal(circumferential) polarization state”) in a lens aperture (pupil plane)of the projection optical system (cf. Patent Document 1).

Patent Document 1: Japanese Patent Application Laid-Open No. 5-90128

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

However, the conventional technology disclosed in the aforementionedpatent document uses a polarizing member disposed on the pupil plane ofthe projection optical system, to transmit only linearly polarizedcomponents vibrating in the circumferential direction, thereby settingthe polarization state of exposure light in the lens aperture to theazimuthal polarization state. This resulted in causing a very large lossof light quantity in the polarizing member and thus brought thedisadvantage of reduction in throughput of the exposure apparatus.

An object of the present invention is to provide an optical systemcapable of achieving a substantially azimuthal polarization state in thelens aperture while suppressing the loss of light quantity, based on asimple configuration. Another object of the present invention is toprovide an exposure apparatus and exposure method capable of forming ahigh-contrast image of a microscopic pattern of a mask on aphotosensitive substrate to effect high-throughput and faithfulexposure, using an optical system capable of achieving a substantiallyazimuthal polarization state in the lens aperture while suppressing theloss of light quantity.

Means for Solving the Problem

In order to achieve the above object, a first aspect of the presentinvention provides an optical system comprising a birefringent elementfor achieving a substantially circumferential distribution or asubstantially radial distribution as a fast axis distribution in a lensaperture; and an optical rotator disposed behind the birefringentelement and adapted to rotate a polarization state in the lens aperture.

A second aspect of the present invention provides an optical systemcomprising:

a birefringent optical rotator which is made of an optical material withlinear birefringence and optical rotatory power and an optic axis ofwhich is arranged substantially in parallel with an optical axis of theoptical system,

wherein a light beam in a substantially circular polarization state isincident to the birefringent optical rotator.

A third aspect of the present invention provides an exposure apparatuscomprising the optical system of the first aspect or the second aspect,wherein a pattern of a mask is projected through the optical system ontoa photosensitive substrate to effect exposure thereof.

A fourth aspect of the present invention provides an exposure method ofprojecting a pattern formed in a mask, through the optical system of thefirst aspect or the second aspect onto a photosensitive substrate toeffect exposure thereof.

EFFECTS OF THE INVENTION

The present invention provides the optical system capable of achievingthe substantially azimuthal polarization state in the lens aperturewhile suppressing the loss of light quantity, based on the simpleconfiguration, for example, through collaboration of the birefringentelement for achieving the substantially circumferential distribution orthe substantially radial distribution as the fast axis distribution inthe lens aperture, and the optical rotator disposed behind thebirefringent element and adapted to rotate the polarization state in thelens aperture.

Since the exposure apparatus and exposure method of the presentinvention use the optical system capable of achieving the substantiallyazimuthal polarization state in the lens aperture while suppressing theloss of light quantity, they allow us to form a high-contrast image of amicroscopic pattern of a mask on a photosensitive substrate to effecthigh-throughput and faithful exposure and, eventually, to fabricate gooddevices at high throughput.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing schematically showing a configuration of an exposureapparatus according to an embodiment of the present invention.

FIG. 2 is a drawing for explaining an action of a conical axicon systemon an annular secondary light source.

FIG. 3 is a drawing for explaining an action of a zoom lens on anannular secondary light source.

FIG. 4 is a perspective view schematically showing an internalconfiguration of a polarization monitor in FIG. 1.

FIG. 5 is a drawing schematically showing a major configuration of anexposure apparatus according to an embodiment of the present invention,to show a configuration from a mask blind to a wafer.

FIG. 6 shows (a) a linear polarization state of circumferentialvibration in a lens aperture, and (b) a linear polarization state ofradial vibration in a lens aperture.

FIG. 7 is a drawing showing a state in which a birefringent element andan optical rotator are provided at predetermined positions in an opticalpath of an optical system telecentric on the object side.

FIG. 8 shows (a) a circumferential fast axis distribution in a lensaperture, and (b) a radial fast axis distribution in a lens aperture.

FIG. 9 is a drawing showing a polarization distribution in a lensaperture of circularly polarized light incident to a birefringentelement.

FIG. 10 is a drawing showing polarization distributions in a lensaperture of a light beam having passed through a birefringent element.

FIG. 11 is a drawing showing a polarization distribution in a lensaperture obtained through a birefringent element and an optical rotator.

FIG. 12 is a drawing schematically showing a major configuration of anexposure apparatus according to a first modification example of theembodiment of the present invention.

FIG. 13 is a drawing schematically showing a major configuration of anexposure apparatus according to a second modification example of theembodiment of the present invention.

FIG. 14 is a drawing schematically showing a major configuration of anexposure apparatus according to a third modification example of theembodiment of the present invention.

FIG. 15 is a drawing schematically showing a major configuration of anexposure apparatus according to a fourth modification example of theembodiment of the present invention.

FIG. 16 is a drawing schematically showing a major configuration of anexposure apparatus according to a fifth modification example of theembodiment of the present invention.

FIG. 17 is a drawing schematically showing a major configuration of anexposure apparatus according to a sixth modification example of theembodiment of the present invention.

FIG. 18 is a drawing for explaining change of polarization states in abirefringent optical rotator with the Poincare sphere.

FIG. 19 is a drawing schematically showing a major configuration of anexposure apparatus according to a seventh modification example of theembodiment of the present invention.

FIG. 20 is a drawing schematically showing a major configuration of anexposure apparatus according to an eighth modification example of theembodiment of the present invention.

FIG. 21 is a drawing schematically showing a major configuration of anexposure apparatus according to a ninth modification example of theembodiment of the present invention.

FIG. 22 is a drawing schematically showing a major configuration of anexposure apparatus according to a tenth modification example of theembodiment of the present invention.

FIG. 23 is a drawing schematically showing a major configuration of anexposure apparatus according to an eleventh modification example of theembodiment of the present invention.

FIG. 24 is a drawing schematically showing a major configuration of anexposure apparatus according to a twelfth modification example of theembodiment of the present invention.

FIG. 25 is a drawing schematically showing a major configuration of anexposure apparatus according to a thirteenth modification example of theembodiment of the present invention.

FIG. 26 is a drawing schematically showing a major configuration of anexposure apparatus according to a fourteenth modification example of theembodiment of the present invention.

FIG. 27 is a drawing schematically showing a major configuration of anexposure apparatus according to a fifteenth modification example of theembodiment of the present invention.

FIG. 28 is a flowchart of a technique of fabricating semiconductordevices as micro devices.

FIG. 29 is a flowchart of a technique of fabricating a liquid-crystaldisplay element as a micro device.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described based on theaccompanying drawings. FIG. 1 is a drawing schematically showing aconfiguration of an exposure apparatus according to an embodiment of thepresent invention. In FIG. 1, the Z-axis is set along a direction of anormal to a wafer W being a photosensitive substrate, the Y-axis along adirection parallel to the plane of FIG. 1 in the plane of the wafer W,and the X-axis along a direction normal to the plane of FIG. 1 in theplane of the wafer W. With reference to FIG. 1, the exposure apparatusof the present embodiment is provided with a light source 1 forsupplying exposure light (illumination light).

The light source 1 can be, for example, a KrF excimer laser light sourcefor supplying light of wavelength of 248 nm or an ArF excimer laserlight source for supplying light of wavelength of 193 nm. A nearlyparallel light beam emitted along the Z-direction from the light source1 has a rectangular cross section extending oblongly along theX-direction, and is incident to a beam expander 2 consisting of a pairof lenses 2 a and 2 b. The lenses 2 a and 2 b have a negative refractingpower and a positive refracting power, respectively, in the plane ofFIG. 1 (YZ plane). Therefore, the light beam incident to the beamexpander 2 is expanded in the plane of FIG. 1 to be shaped into a lightbeam having a cross section of a predetermined rectangular shape.

The nearly parallel light beam having passed through the beam expander 2as a shaping optical system is deflected into the Y-direction by abending mirror 3, then travels through a quarter-wave plate 4 a, ahalf-wave plate 4 b, a depolarizer (depolarizing element) 4 c, and adiffractive optical element 5 for annular illumination, and then isincident to an afocal lens 6. The quarter-wave plate 4 a, half-waveplate 4 b, and depolarizer 4 c herein constitute a polarization stateconverter 4, as described later. The afocal lens 6 is an afocal system(afocal optical system) the front focal point of which agreesapproximately with the position of the diffractive optical element 5 andthe rear focal point of which agrees approximately with a position of apredetermined plane 7 indicated by a dashed line in the drawing.

In general, a diffractive optical element is constructed by formingsteps with a pitch approximately equal to the wavelength of exposurelight (illumination light), in a substrate, and has an action todiffract an incident beam into desired angles. Specifically, thediffractive optical element 5 for annular illumination has the followingfunction: when a parallel light beam having a rectangular cross sectionis incident thereto, it forms an optical intensity distribution of anannular shape in its far field (or Fraunhofer diffraction region).

Therefore, the nearly parallel light beam incident to the diffractiveoptical element 5 as a light beam converter forms an optical intensitydistribution of an annular shape on the pupil plane of the afocal lens 6and then emerges as a nearly parallel light beam from the afocal lens 6.A conical axicon system 8 is located at or near the pupil plane in anoptical path between front lens unit 6 a and rear lens unit 6 b of theafocal lens 6, and its detailed configuration and action will bedescribed later. For simplifying the description, the basicconfiguration and action will be described below in disregard for theaction of conical axicon system 8.

The light beam having passed through the afocal lens 6 travels through azoom lens 9 for variation of o-value and then is incident to a microfly's eye lens (or fly's eye lens) 10 as an optical integrator. Themicro fly's eye lens 10 is an optical element consisting of a lot ofmicrolenses with a positive refracting power arranged vertically andhorizontally and densely. In general, a micro fly's eye lens isconstructed, for example, by etching a plane-parallel plate so as toform a microlens group.

It is noted herein that each microlens forming the micro fly's eye lensis smaller than each lens element forming a fly's eye lens. The microfly's eye lens is one in which a lot of microlenses (micro refractingsurfaces) are integrally formed without being isolated from each other,different from the fly's eye lens consisting of lens elements isolatedfrom each other. However, the micro fly's eye lens is also an opticalintegrator of the same wavefront splitting type as the fly's eye lens interm of the vertical and horizontal arrangement of the lens elementswith the positive refracting power.

The position of the predetermined plane 7 is defined near the frontfocal position of the zoom lens 9 and the incidence surface of the microfly's eye lens 10 is defined near the rear focal position of the zoomlens 9. In other words, the zoom lens 9 keeps the predetermined plane 7and the incidence surface of the micro fly's eye lens 10 substantiallyin the relation of Fourier transform and, consequently, keeps the pupilplane of the afocal lens 6 optically nearly conjugate with the incidencesurface of the micro fly's eye lens 10.

Therefore, for example, an illumination field of an annular shape aroundthe optical axis AX, similar to that on the pupil plane of the afocallens 6, is formed on the incidence surface of the micro fly's eye lens10. The entire shape of this annular illumination field similarly variesdepending upon the focal length of the zoom lens 9. Each microlensforming the micro fly's eye lens 10 has a rectangular cross sectionsimilar to a shape of an illumination field to be formed on a mask M(i.e., eventually, a shape of an exposure region to be formed on a waferW).

The light beam incident to the micro fly's eye lens 10 istwo-dimensionally split by a lot of microlenses to form a secondarylight source having an optical intensity distribution approximatelyequal to the illumination field formed by the incident light beam, i.e.,a secondary light source of a substantive surface illuminant of anannular shape around the optical axis AX, on the rear focal plane(consequently, on the illumination pupil). A light beam from thesecondary light source formed on the rear focal plane of the micro fly'seye lens 10 travels through beam splitter 11 a and condenser opticalsystem 12 to illuminate a mask blind 13 in a superposed manner.

In this manner, an illumination field of a rectangular shape accordingto the shape and the focal length of each microlens forming the microfly's eye lens 10 is formed on the mask blind 13 as an illuminationfield stop. An internal configuration and action of a polarizationmonitor 11 incorporating the beam splitter 11 a will be described later.A light beam having passed through an aperture (light transmitting part)of a rectangular shape of the mask blind 13 is subjected to focusingaction of an imaging optical system 14 and thereafter illuminates themask M with a predetermined pattern therein, in a superposed andapproximately telecentric manner.

Namely, the imaging optical system 14 forms an image of the rectangularaperture of the mask blind 13 on the mask M. A light beam having passedthrough the pattern of the mask M then travels through a projectionoptical system PL which is approximately telecentric both on the objectside and on the image side, to form an image of the mask pattern on awafer W being a photosensitive substrate. While the wafer W istwo-dimensionally driven and controlled in the plane (XY plane)perpendicular to the optical axis AX of the projection optical systemPL, one-shot exposure or scan exposure is effected so that the patternof the mask M sequentially exposed into each of exposure regions on thewafer W.

In the polarization state converter 4, the quarter-wave plate 4 a isarranged so that the crystallographic axis thereof is rotatable aroundthe optical axis AX, and converts incident light of ellipticpolarization into light of linear polarization. The half-wave plate 4 bis arranged so that the crystallographic axis thereof is rotatablearound the optical axis AX, and changes the plane of polarization ofincident linearly polarized light. The depolarizer 4 c is composed of arock crystal prism of wedge shape (not shown) and a silica prism ofwedge shape (not shown) having complementary shapes. The rock crystalprism and the silica prism are constructed as an integral prism assemblyso as to be freely inserted into or retracted from the illuminationoptical path.

Where the light source 1 is a KrF excimer laser light source or an ArFexcimer laser light source, light emitted from these light sourcestypically has the degree of polarization of not less than 95% and nearlylinearly polarized light is incident to the quarter-wave plate 4 a.However, if a right-angle prism is interposed as a back reflector in theoptical path between the light source 1 and the polarization stateconverter 4, total reflection in the right-angle prism will convertlinear polarization into elliptic polarization unless the plane ofpolarization of the incident linearly polarized light coincides with thep-polarization plane or s-polarization plane.

In the polarization state converter 4, for example, even if light ofelliptic polarization is incident because of the total reflection in theright-angle prism, it will be converted into light of linearpolarization by the action of the quarter-wave plate 4 a and thelinearly polarized light will be incident to the half-wave plate 4 b.When the crystallographic axis of the half-wave plate 4 b is set at anangle of 0° or 90° relative to the plane of polarization of incidentlinearly polarized light, the light of linear polarization incident tothe half-wave plate 4 b passes directly without change in the plane ofpolarization.

When the crystallographic axis of the half-wave plate 4 b is set at anangle of 45° relative to the plane of polarization of incident linearlypolarized light, the light of linear polarization incident to thehalf-wave plate 4 b is converted into light of linear polarization withthe plane of polarization changed by 90°. Furthermore, when thecrystallographic axis of the rock crystal prism of the depolarizer 4 cis set at an angle of 45° relative to the plane of polarization ofincident linearly polarized light, the light of linear polarizationincident to the rock crystal prism is converted (or depolarized) intolight in an unpolarized state.

The polarization state converter 4 is arranged so that thecrystallographic axis of the rock crystal prism makes the angle of 45°relative to the plane of polarization of incident linearly polarizedlight when the depolarizer 4 c is positioned in the illumination opticalpath. Incidentally, if the crystallographic axis of the rock crystalprism is set at an angle of 0° or 90° relative to the plane ofpolarization of incident linearly polarized light, the light of linearpolarization incident to the rock crystal prism will pass directlywithout change in the plane of polarization. When the crystallographicaxis of the half-wave plate 4 b is set at an angle of 22.5° relative tothe plane of polarization of incident linearly polarized light, thelight of linear polarization incident to the half-wave plate 4 b isconverted into light in an unpolarized state including a linearpolarization component passing without change in the plane ofpolarization, and a linear polarization component with the plane ofpolarization changed by 90°.

In the polarization state converter 4, as described above, the light oflinear polarization is incident to the half-wave plate 4 b, and let usassume herein that light of linear polarization with the polarizationdirection (the direction of the electric field) along the Z-direction inFIG. 1 (which will be referred to hereinafter as “Z-directionalpolarization”) is incident to the half-wave plate 4 b, forsimplification of the description hereinafter. When the depolarizer 4 cis positioned in the illumination optical path and when thecrystallographic axis of the half-wave plate 4 b is set at the angle of0° or 90° relative to the plane of polarization (direction ofpolarization) of incident Z-directionally polarized light, the light ofZ-directional polarization incident to the half-wave plate 4 b passes asZ-directionally polarized light without change in the plane ofpolarization and then is incident to the rock crystal prism of thedepolarizer 4 c. Since the crystallographic axis of the rock crystalprism is set at the angle of 45° relative to the plane of polarizationof the incident Z-directionally polarized light, the light ofZ-directional polarization incident to the rock crystal prism isconverted into light in an unpolarized state.

The light depolarized through the rock crystal prism travels through thesilica prism as a compensator for compensating the traveling directionof light, and is then incident in an unpolarized state, into thediffractive optical element 5. On the other hand, when thecrystallographic axis of the half-wave plate 4 b is set at the angle of45° relative to the plane of polarization of the incidentZ-directionally polarized light, the light of Z-directional polarizationincident to the half-wave plate 4 b is converted into light with theplane of polarization changed by 90°, i.e., light of linear polarizationhaving the direction of polarization (direction of the electric field)along the X-direction in FIG. 1 (which will be referred to hereinafteras “X-directional polarization”) to be incident to the rock crystalprism of the depolarizer 4 c. Since the crystallographic axis of therock crystal prism is also set at the angle of 45° relative to the planeof polarization of the incident X-directionally polarized light, thelight of the X-directional polarization incident to the rock crystalprism is converted into light in an unpolarized state to travel throughthe silica prism and then to be incident in an unpolarized state to thediffractive optical element 5.

In contrast to it, when the depolarizer 4 c is retracted from theillumination optical path and when the crystallographic axis of thehalf-wave plate 4 b is set at the angle of 0° or 90° relative to theplane of polarization of the incident Z-directionally polarized light,the light of Z-directional polarization incident to the half-wave plate4 b passes as Z-directionally polarized light without change in theplane of polarization, and is incident in a Z-directional polarizationstate to the diffractive optical element 5. On the other hand, when thecrystallographic axis of the half-wave plate 4 b is set at the angle of45° relative to the plane of polarization of the incidentZ-directionally polarized light, the light of Z-directional polarizationincident to the half-wave plate 4 b is converted into light ofX-directional polarization with the plane of polarization changed by90°, and is incident in an X-directional polarization state to thediffractive optical element 5.

As described above, the polarization state converter 4 is able to makethe light in an unpolarized state incident to the diffractive opticalelement 5 when the depolarizer 4 c is inserted and positioned in theillumination optical path. It is also able to make the light in aZ-directional polarization state incident to the diffractive opticalelement 5 when the depolarizer 4 c is retracted from the illuminationoptical path and when the crystallographic axis of the half-wave plate 4b is set at the angel of 0° or 90° relative to the plane of polarizationof the incident Z-directionally polarized light. Furthermore, it is alsoable to make the light in an X-directional polarization state incidentto the diffractive optical element 5 when the depolarizer 4 c isretracted from the illumination optical path and when thecrystallographic axis of the half-wave plate 4 b is set at the angel of45° relative to the plane of polarization of the incidentZ-directionally polarized light.

In other words, the polarization state converter 4 is able to switch thepolarization state of incident light to the diffractive optical element5 (consequently, the polarization state of light to illuminate the maskM and wafer W) between a linear polarization state and an unpolarizedstate and, in the case of the linear polarization state, it is able toswitch the polarization of incident light between polarization statesorthogonal to each other (i.e., between Z-directional polarization andX-directional polarization), through the action of the polarizationstate converter consisting of the quarter-wave plate 4 a, half-waveplate 4 b, and depolarizer 4 c.

Furthermore, the polarization state converter 4 is able to make light ina circular polarization state incident to the diffractive opticalelement 5 (consequently, to after-described birefringent element 21)when the half-wave plate 4 b and depolarizer 4 c both are retracted fromthe illumination optical path and when the crystallographic axis of thequarter-wave plate 4 a is set at a predetermined angle relative toincident elliptically polarized light.

The conical axicon system 8 is composed of a first prism member 8 a aplane of which faces the light source side and a refracting surface of aconcave conical shape of which faces the mask side, and a second prismmember 8 b a plane of which faces the mask side and a refracting surfaceof a convex conical shape of which faces the light source side, in orderfrom the light source side. Then the refracting surface of the concaveconical shape of the first prism member 8 a and the refracting surfaceof the convex conical shape of the second prism member 8 b are formed insuch complementary shapes as to be able to butt each other. At least oneof the first prism member 8 a and the second prism member 8 b isarranged movable along the optical axis AX to vary the distance betweenthe refracting surface of the concave conical shape of the first prismmember 8 a and the refracting surface of the convex conical shape of thesecond prism member 8 b.

In a state in which the refracting surface of the concave conical shapeof the first prism member 8 a butts against the refracting surface ofthe convex conical shape of the second prism member 8 b, the conicalaxicon system 8 functions as a plane-parallel plate and has no effect onthe secondary light source of annular shape formed. However, when therefracting surface of the concave conical shape of the first prismmember 8 a is located apart from the refracting surface of the convexconical shape of the second prism member 8 b, the conical axicon system8 functions as a so-called beam expander. Therefore, the angle of theincident light beam to the predetermined plane 7 varies with change inthe distance of the conical axicon system 8.

FIG. 2 is a drawing for explaining the action of the conical axiconsystem on a secondary light source of annular shape. With reference toFIG. 2, a secondary light source 30 a of the smallest annular shapeformed in a state in which the distance of the conical axicon system 8is zero and in which the focal length of the zoom lens 9 is set to aminimum (hereinafter referred to as “standard state”) is changed into asecondary light source 30 b of an annular shape with the outsidediameter and inside diameter both increased, without change in the widththereof (half of the difference between the outside diameter and insidediameter: indicated by arrows in the drawing) when the distance of theconical axicon system 8 is increased from zero to a predetermined value.In other words, the annular ratio (inside diameter/outside diameter) andsize (outside diameter) of the secondary light source both vary withoutchange in the width of the annular secondary light source, through theaction of the conical axicon system 8.

FIG. 3 is a drawing for explaining the action of the zoom lens on thesecondary light source of annular shape. With reference to FIG. 3, thesecondary light source 30 a of the annular shape formed in the standardstate is changed into a secondary light source 30 c of an annular shapethe entire shape of which is expanded into a similar shape, when thefocal length of the zoom lens 9 is increased from a minimum value to apredetermined value. In other words, the width and size (outsidediameter) of the secondary light source both vary, without change in theannular ratio of the annular secondary light source, through the actionof the zoom lens 9.

FIG. 4 is a perspective view schematically showing an internalconfiguration of the polarization monitor in FIG. 1. With reference toFIG. 4, the polarization monitor 11 is provided with the first beamsplitter 11 a located in the optical path between the micro fly's eyelens 10 and the condenser optical system 12. The first beam splitter 11a has, for example, a form of a non-coated plane-parallel plate (i.e.,raw glass) made of a silica glass, and has a function of extractingreflected light in a polarization state different from a polarizationstate of incident light, from the optical path.

The light extracted from the optical path by the first beam splitter 11a is incident to a second beam splitter 11 b. The second beam splitter11 b, similar to the first beam splitter 11 a, has a form of anon-coated plane-parallel plate made of a silica glass, for example, andhas a function of generating reflected light in a polarization statedifferent from a polarization state of incident light. The first beamsplitter 11 a and the second beam splitter 11 b are so set that thep-polarization for the first beam splitter 11 a is the s-polarizationfor the second beam splitter 11 b and that the s-polarization for thefirst beam splitter 11 a is the p-polarization for the second beamsplitter 11 b.

Light transmitted by the second beam splitter 11 b is detected by afirst optical intensity detector 11 c and light reflected by the secondbeam splitter 11 b is detected by a second optical intensity detector 11d. Outputs from the first optical intensity detector 11 c and from thesecond optical intensity detector 11 d are supplied respectively to acontroller (not shown). The controller actuates the quarter-wave plate 4a, half-wave plate 4 b, and depolarizer 4 c constituting thepolarization state converter 4, according to need.

In the first beam splitter 11 a and the second beam splitter 11 b, asdescribed above, the reflectance for the p-polarization is substantiallydifferent from the reflectance for the s-polarization. In thepolarization monitor 11, therefore, the reflected light from the firstbeam splitter 11 a includes, for example, an s-polarization component(which is an s-polarization component for the first beam splitter 11 abut p-polarization component for the second beam splitter 11 b) which isapproximately 10% of incident light to the first beam splitter 11 a,and, for example, a p-polarization component (which is a p-polarizationcomponent for the first beam splitter 11 a but s-polarization componentfor the second beam splitter 11 b) which is approximately 1% of incidentlight to the first beam splitter 11 a.

The reflected light from the second beam splitter 11 b includes, forexample, a p-polarization component (which is a p-polarization componentfor the first beam splitter 11 a but s-polarization component for thesecond beam splitter 11 b) which is approximately 10%×1%=0.1% ofincident light to the first beam splitter 11 a, and, for example, ans-polarization component (which is an s-polarization component for thefirst beam splitter 11 a but p-polarization component for the secondbeam splitter 11 b) which is approximately 1%×10%=0.1% of incident lightto the first beam splitter 11 a.

In the polarization monitor 11, as described above, the first beamsplitter 11 a has the function of extracting reflected light in apolarization state different from a polarization state of incidentlight, from the optical path in accordance with its reflectioncharacteristic. In consequence, the polarization monitor 11 is able todetect the polarization state (degree of polarization) of incident lightto the first beam splitter 11 a and thus the polarization state ofillumination light to the mask M, based on the output of the firstoptical intensity detector 11 c (information about the intensity oftransmitted light from the second beam splitter 11 b, i.e., informationabout the intensity of light in much the same polarization state as thereflected light from the first beam splitter 11 a), though slightlyaffected by variation in polarization due to the polarizationcharacteristic of the second beam splitter 11 b.

In addition, the polarization monitor 11 is so set that thep-polarization for the first beam splitter 11 a is the s-polarizationfor the second beam splitter 11 b and that the s-polarization for thefirst beam splitter 11 a is the p-polarization for the second beamsplitter 11 b. As a result, the polarization monitor 11 is able todetect the quantity (intensity) of incident light to the first beamsplitter 11 a and thus the quantity of illumination light to the mask M,without substantially being affected by change in the polarization stateof incident light to the first beam splitter 11 a, based on the outputof the second optical intensity detector 11 d (information about theintensity of the light successively reflected by the first beam splitter11 a and the second beam splitter 11 b).

The polarization monitor 11 is used in this manner to detect thepolarization state of incident light to the first beam splitter 11 a andthus to determine whether the illumination light to the mask M is in adesired unpolarized state, linear polarization state, or circularpolarization state. When the controller confirms that the illuminationlight to the mask M (and thus to the wafer W) is not in the desiredunpolarized state, linear polarization state, or circular polarizationstate, based on the result of the detection by the polarization monitor11, it actuates and adjusts the quarter-wave plate 4 a, half-wave plate4 b, and depolarizer 4 c constituting the polarization state converter 4to adjust the state of the illumination light to the mask M to thedesired unpolarized state, linear polarization state, or circularpolarization state.

When a diffractive optical element for quadrupole illumination (notshown) is set in the illumination optical path, instead of thediffractive optical element 5 for annular illumination, it can effectquadrupole illumination. The diffractive optical element for quadrupoleillumination has the following function: when a parallel light beamhaving a rectangular cross section is incident thereto, it forms anoptical intensity distribution of quadrupole shape in its far field.Therefore, a light beam having passed through the diffractive opticalelement for quadrupole illumination forms an illumination field ofquadrupole shape consisting of four circular illumination fields aroundthe optical axis AX, for example, on the incidence surface of the microfly's eye lens 10. As a result, a secondary light source of the samequadrupole shape as the illumination field formed on the incidencesurface is also formed on the rear focal plane of the micro fly's eyelens 10.

When a diffractive optical element for circular illumination (not shown)is set in the illumination optical path, instead of the diffractiveoptical element 5 for annular illumination, it can effect normalcircular illumination. The diffractive optical element for circularillumination has the following function: when a parallel light beamhaving a rectangular cross section is incident thereto, it forms anoptical intensity distribution of circular shape in the far field.Therefore, a light beam having passed through the diffractive opticalelement for circular illumination forms an illumination field ofquadrupole shape consisting of a circular illumination field around theoptical axis AX, for example, on the incidence surface of the microfly's eye lens 10. As a result, the secondary light source of the samecircular shape as the illumination field formed on the incidence surfaceis also formed on the rear focal plane of the micro fly's eye lens 10.

Furthermore, when another diffractive optical element for multi-poleillumination (not shown) is set in the illumination optical path,instead of the diffractive optical element 5 for annular illumination,it is feasible to implement one of various multi-pole illuminations(dipole illumination, octupole illumination, etc.). When the diffractiveoptical element 5 for annular illumination is replaced by a diffractiveoptical element (not shown) for forming an optical intensitydistribution of an annular shape having an annular ratio different fromthat of the diffractive optical element 5, in its far field as set inthe illumination optical path, it can expand the varying range of theannular ratio. Similarly, when the diffractive optical element 5 forannular illumination is replaced by a diffractive optical element withan appropriate characteristic (not shown) as set in the illuminationoptical path, it becomes feasible to implement one of illuminations ofvarious forms.

FIG. 5 is a drawing schematically showing a major configuration of theexposure apparatus according to the present embodiment, and shows aconfiguration from the mask blind to the wafer. With reference to FIG.5, the exposure apparatus of the present embodiment is so arranged thata birefringent element 21 is located in the optical path between themask blind 13 and the imaging optical system 14 and that an opticalrotator 22 is located at a predetermined position in the optical path ofthe imaging optical system 14. The present embodiment achieves a nearlyazimuthal polarization state in a lens aperture of an optical system (acombined optical system of the illumination optical system (2-14) withthe projection optical system PL) through collaboration of thebirefringent element 21 and the optical rotator 22.

The general action of the birefringent element 21 and optical rotator22, i.e., the basic principle of the present invention will be describedbelow. In the present invention, linear polarization of circumferentialvibration in the lens aperture of the optical system is defined asazimuthal polarization as shown in FIG. 6 (a), and linear polarizationof radial vibration in the lens aperture as radial polarization as shownin FIG. 6 (b). In this case, coherency of two rays on the image plane inthe optical system having a large image-side numerical aperture ishigher in azimuthal polarization than in radial polarization. Therefore,when the polarization state of light in the lens aperture is set to anearly azimuthal polarization state, a high-contrast object image can beobtained on the image plane.

In the present invention, therefore, in order to realize the nearlyazimuthal polarization state in the lens aperture, as shown in FIG. 7,the birefringent element 21 and optical rotator 22 are provided atpredetermined positions in the optical path of the optical system whichis telecentric on the object side, for example. The birefringent element21 is, for example, an optically transparent member of a plane-parallelplate shape made of a uniaxial crystal like rock crystal, and thecrystallographic axis thereof is arranged in parallel with the opticalaxis AX. In this case, when a light beam of spherical waves is madeincident to the birefringent element 21 made of a positive uniaxialcrystal, a circumferential distribution around the optical axis AX isobtained as a fast axis distribution in the lens aperture of the opticalsystem, as shown in FIG. 8 (a).

On the other hand, if a light beam of spherical waves is made incidentto the birefringent element 21 made of a negative uniaxial crystal, aradial distribution around the optical axis AX is obtained as a fastaxis distribution in the lens aperture of the optical system, as shownin FIG. 8 (b). Let us suppose herein that a light beam of sphericalwaves in a circular polarization state having a polarizationdistribution in the lens aperture as shown in FIG. 9 is made incident tothe birefringent element 21. Then the light beam having passed throughthe birefringent element 21 comes to have a polarization distribution inthe lens aperture as shown in FIG. 10 (a) or (b).

The polarization distribution shown in FIG. 10 (a) is obtained whenclockwise circularly polarized light as shown in FIG. 9 is made incidentto the birefringent element 21 corresponding to the fast axisdistribution of FIG. 8 (a), i.e., the birefringent element 21 made of apositive uniaxial crystal. On the other hand, the polarizationdistribution shown in FIG. 10 (b) is obtained when clockwise circularlypolarized light as shown in FIG. 9 is made incident to the birefringentelement 21 corresponding to the fast axis distribution of FIG. 8 (b),i.e., the birefringent element 21 made of a negative uniaxial crystal.

The optical rotator 22 is, for example, an optically transparent memberof a plane-parallel plate shape made of an optical material with opticalrotatory power like rock crystal, and is located behind the birefringentelement 21 (on the image side). The optical rotator 22 is arranged sothat the crystallographic axis thereof is parallel to the optical axisAX, and has a function of rotating a polarization state in a lensaperture by a predetermined angle according to a thickness thereof, anangle of incidence of a light beam, or the like. In the presentinvention, the polarization state of the light beam having passedthrough the birefringent element 21 is rotated by 45° (i.e., thepolarization state in the lens aperture is rotated by 45°) by the actionof the optical rotator 22, to obtain a polarization distribution in thelens aperture as shown in FIG. 11.

However, where the birefringent element 21 is one made of a positiveuniaxial crystal, the birefringent element 21 provides the polarizationdistribution shown in FIG. 10 (a) and it is thus necessary to use theoptical rotator 22 made of an optical material with counterclockwiseoptical rotatory power in order to obtain the polarization distributionin the lens aperture as shown in FIG. 11. On the other hand, where thebirefringent element 21 is one made of a negative uniaxial crystal, thebirefringent element 21 provides the polarization distribution shown inFIG. 10 (b) and it is thus necessary to use the optical rotator 22 madeof an optical material with clockwise optical rotatory power in order toobtain the polarization distribution in the lens aperture as shown inFIG. 11.

It is seen with reference to the polarization distribution in the lensaperture shown in FIG. 11 that a ray passing the center (optical axisAX) of the lens aperture is in a circular polarization state,polarization states vary from an elliptic polarization state to a linearpolarization state toward the periphery of the aperture, and thepolarization states are distributed with rotational symmetry withrespect to the optical axis AX. In the polarization distribution in thelens aperture shown in FIG. 11, as described above, the azimuthalpolarization state (linear polarization state of circumferentialvibration around the optical axis AX) is not achieved throughout thewhole area in the lens aperture, but the azimuthal polarization state isachieved at least in the peripheral region of the lens aperture.

When consideration is given to the fact that degradation of coherency information of image is greater for rays in the peripheral region of thelens aperture than for rays in the central region of the lens aperture,the polarization distribution in which the azimuthal polarization stateis achieved in the peripheral region of the lens aperture as shown inFIG. 11 is approximately equivalent to the polarization distribution inwhich the azimuthal polarization state is achieved throughout the wholearea of the lens aperture as shown in FIG. 6 (a), in terms ofimprovement in the contrast of the object image. In the presentinvention, as described above, the nearly azimuthal polarization statein the lens aperture can be realized through collaboration of thebirefringent element 21 and optical rotator 22, whereby thehigh-contrast object image can be obtained eventually on the imageplane. In the polarization distribution in the lens aperture shown inFIG. 11, the azimuthal polarization state is achieved in the outermostperipheral region of the lens aperture, but the region in the lensaperture where the azimuthal polarization state is achieved does nothave to be limited to the outermost periphery. The region can beappropriately set according to need. When the polarization distributionwhere the azimuthal polarization state is achieved in the peripheralregion of the lens aperture as shown in FIG. 11 is combined with theannular illumination or multi-pole illumination such as dipole orquadrupole illumination, the polarization distribution in theillumination light beam turns into a nearly azimuthal polarization stateand thus a higher-contrast object image can be obtained on the imageplane.

The birefringent element can be an optically transparent member made ofan appropriate optical material except for rock crystal, e.g., anoptical material with linear birefringence such as MgF₂ or LiCaAlF₆(lithium calcium aluminum fluoride). In another potential example, thebirefringent element is, for example, a pair of optically transparentmembers made of a crystal material of the cubic system like fluorite,and the pair of optically transparent members are positioned so that thefast axis distribution in the lens aperture becomes a nearlycircumferential distribution or a nearly radial distribution.

Specifically, the birefringent element can be a pair of opticallytransparent members arranged in a state in which the crystal orientation<111> is parallel to the optical axis and in which the other crystalorientations are relatively rotated by about 60° around the opticalaxis. In this case, when a light beam of spherical waves is madeincident to the birefringent element consisting of the pair of opticallytransparent members, a circumferential distribution about the opticalaxis AX is obtained as the fast axis distribution in the lens apertureof the optical system as shown in FIG. 8 (a), just as in the case of thebirefringent element made of a positive uniaxial crystal. Accordingly,when a light beam of spherical waves is made incident in a clockwisecircular polarization state as shown in FIG. 9, the polarizationdistribution in the lens aperture as shown in FIG. 10 (a) is obtained.

The birefringent element can also be a pair of optically transparentmembers arranged in a state in which the crystal orientation <100> isapproximately parallel to the optical axis and in which the othercrystal orientations are relatively rotated by about 45° around theoptical axis. In this case, when a light beam of spherical waves is madeincident to the birefringent element consisting of the pair of opticallytransparent members, a radial distribution around the optical axis AX isobtained as the fast axis distribution in the lens aperture of theoptical system as shown in FIG. 8 (b), just as in the case of thebirefringent element made of a negative uniaxial crystal. Therefore,when a light beam of spherical waves is made incident in a clockwisecircular polarization state as shown in FIG. 9, the polarizationdistribution in the lens aperture as shown in FIG. 10 (b) is obtained.

The birefringent element made of the uniaxial crystal, and thebirefringent element consisting of the pair of optically transparentmembers made of the crystal material of the cubic system are elements inwhich the amount of birefringence varies according to angles ofincidence. Therefore, when a light beam of spherical waves is madeincident, the birefringent element functions as one having the fast axisdistribution as shown in FIG. 8 (a) or (b), to obtain the polarizationdistribution in the lens aperture as shown in FIG. 10 (a) or (b). Formaking the polarization distribution in the lens aperture approximatelyuniform in the plane, as shown in FIG. 7, it is preferable to place thebirefringent element of a uniaxial crystal (or the birefringent elementconsisting of the pair of optically transparent members) 21 in anapproximately telecentric optical path.

On the other hand, the optical rotator 22 preferably uniformly rotatesthe polarization state in the lens aperture. Therefore, the opticalrotator 22 is preferably located at a position where there is littlevariation in the angle of incidence of the light beam, as shown in FIG.7. Specifically, the optical rotator 22 is preferably located at aposition where the light beam is incident with variation of not morethan 10° in the angle of incidence, and the optical rotator 22 is morepreferably located at a position where the light beam is incident withvariation of not more than 7° in the angle of incidence. Besides rockcrystal, the optical rotator 22 can be made of an appropriate opticalmaterial with optical rotatory power.

Referring again to FIG. 5, the exposure apparatus of the presentembodiment is arranged so that the birefringent element of an opticallytransparent member made of a uniaxial crystal, for example, like rockcrystal (or the birefringent element consisting of a pair of opticallytransparent members made of a crystal material of the cubic system, forexample, like fluorite) 21 is located in the optical path between themask blind 13 and the imaging optical system 14, i.e., in the nearlytelecentric optical path near the mask blind 13 located at the positionoptically conjugate with the mask M being a surface to be illuminated.In addition, the optical rotator 22, for example, made of rock crystalis located at the position where the light beam is incident, forexample, with variation of not more than 10° in the angle of incidence,in the optical path of the imaging optical system 14.

In this state, when the half-wave plate 4 b and depolarizer 4 c both areretracted from the illumination optical path and when thecrystallographic axis of the quarter-wave plate 4 a is set at apredetermined angle relative to incident elliptically polarized light, alight beam of nearly spherical waves is incident in a circularpolarization state to the birefringent element 21. As a result, thepresent embodiment is able to achieve the nearly azimuthal polarizationstate in the lens aperture while suppressing the loss of light quantity,based on the simple configuration, through collaboration of thebirefringent element 21 for achieving the nearly circumferentialdistribution or the nearly radial distribution as the fast axisdistribution in the lens aperture, and the optical rotator 22 disposedbehind it and adapted to rotate the polarization state in the lensaperture. Therefore, the present embodiment is able to form thehigh-contrast image of the microscopic pattern of the mask M on thewafer W to effect high-throughput and faithful exposure.

FIG. 12 is a drawing schematically showing a major configuration of anexposure apparatus according to a first modification example of thepresent embodiment. In the first modification example, the configurationfrom the mask blind 13 to the wafer W is similar to that in theembodiment shown in FIG. 5. However, the first modification example isdifferent from the embodiment shown in FIG. 5, in that the birefringentelement 21 is located in the optical path between the imaging opticalsystem 14 and the mask M and in that the optical rotator 22 is locatedat a predetermined position in the optical path of the projectionoptical system PL.

Namely, in the first modification example the birefringent element 21 islocated in the nearly telecentric optical path near the mask M, in theoptical path of the illumination optical system (2-14). Furthermore, theoptical rotator 22 is located at a position relatively close to the maskM in the optical path of the projection optical system PL, e.g., at aposition where the light beam is incident with variation of not morethan 10° in the angle of incidence. As a result, the first modificationexample is also able to achieve the nearly azimuthal polarization statein the lens aperture while suppressing the loss of light quantity, basedon the simple configuration, through collaboration of the birefringentelement 21 and the optical rotator 22 as the embodiment of FIG. 5 was.

FIG. 13 is a drawing schematically showing a major configuration of anexposure apparatus according to a second modification example of thepresent embodiment. In the second modification example, just as in thefirst modification example, the configuration from the mask blind 13 tothe wafer W is similar to that in the embodiment shown in FIG. 5.However, the second modification example is different from theembodiment shown in FIG. 5, in that the birefringent element 21 islocated in the optical path between the mask M and the projectionoptical system PL and in that the optical rotator 22 is located at apredetermined position in the optical path of the projection opticalsystem PL.

Namely, in the second modification example the birefringent element 21is located in the nearly telecentric optical path near the mask M, inthe optical path of the projection optical system PL.

Furthermore, the optical rotator 22 is located at a position relativelyclose to the mask M in the optical path of the projection optical systemPL, e.g., at a position where the light beam is incident with variationof not more than 10° in the angle of incidence. As a result, the secondmodification example is also able to achieve the nearly azimuthalpolarization state in the lens aperture while suppressing the loss oflight quantity, based on the simple configuration, through collaborationof the birefringent element 21 and the optical rotator 22 as theembodiment of FIG. 5 was.

FIG. 14 is a drawing schematically showing a major configuration of anexposure apparatus according to a third modification example of thepresent embodiment. In the third modification example, just as in thefirst modification example and the second modification example, theconfiguration from the mask blind 13 to the wafer W is similar to thatin the embodiment shown in FIG. 5. However, the third modificationexample is different from the embodiment shown in FIG. 5, in that thebirefringent element 21 is located in the optical path between the maskM and the projection optical system PL and in that the optical rotator22 is located at a predetermined position in the optical path of theprojection optical system PL.

Namely, in the third modification example, as in the second modificationexample, the birefringent element 21 is located in the nearlytelecentric optical path near the mask M (i.e., in the optical pathnearly telecentric on the mask M side), in the optical path of theprojection optical system PL. However, different from the secondmodification example, the optical rotator 22 is located at a positionrelatively close to the wafer W in the optical path of the projectionoptical system PL, e.g., at a position where the light beam is incidentwith variation of not more than 10° in the angle of incidence. As aresult, the third modification example is also able to achieve thenearly azimuthal polarization state in the lens aperture whilesuppressing the loss of light quantity, based on the simpleconfiguration, through collaboration of the birefringent element 21 andthe optical rotator 22 as the embodiment shown in FIG. 5 was.

FIG. 15 is a drawing schematically showing a major configuration of anexposure apparatus according to a fourth modification example of thepresent embodiment. In the fourth modification example the configurationfrom the mask blind 13 to the mask M is similar to that in theembodiment shown in FIG. 5. However, the fourth modification example isdifferent from the embodiment of FIG. 5 in that, while the projectionoptical system PL in the embodiment of FIG. 5 is a dioptric system, theprojection optical system PL of the fourth modification example is acatadioptric system of a threefold imaging type including a concavemirror CM. The fourth modification example is also different from theembodiment shown in FIG. 5, in that the birefringent element 21 islocated in the optical path between the imaging optical system 14 andthe mask M and in that the optical rotator 22 is located at apredetermined position in the optical path of the projection opticalsystem PL.

Namely, in the fourth modification example the birefringent element 21is located in the nearly telecentric optical path near the mask M, inthe optical path of the illumination optical system (2-14). Furthermore,the optical rotator 22 is located at a position relatively close to themask M in an optical path of a first imaging optical system G1 in theprojection optical system PL, e.g., at a position where the light beamis incident with variation of not more than 10° in the angle ofincidence. As a result, the fourth modification example is also able toachieve the nearly azimuthal polarization state in the lens aperturewhile suppressing the loss of light quantity, based on the simpleconfiguration, through collaboration of the birefringent element 21 andthe optical rotator 22 as the embodiment of FIG. 5 was.

FIG. 16 is a drawing schematically showing a major configuration of anexposure apparatus according to a fifth modification example of thepresent embodiment. In the fifth modification example the configurationfrom the mask blind 13 to the mask M is similar to that in the fourthmodification example of FIG. 15. However, the fifth modification exampleis different from the fourth modification example of FIG. 15 in that thebirefringent element 21 is located in the optical path between the maskM and the projection optical system PL and in that the optical rotator22 is located at a predetermined position in the optical path of theprojection optical system PL.

Namely, in the fifth modification example the birefringent element 21 islocated in the nearly telecentric optical path near the mask M (i.e., inthe optical path nearly telecentric on the mask M side), in the opticalpath of the projection optical system PL. Furthermore, the opticalrotator 22 is located at a position relatively close to the wafer W inthe optical path of the first imaging optical system G1 in theprojection optical system PL, e.g., at a position where the light beamis incident with variation of not more than 10° in the angle ofincidence. As a result, the fifth modification example is also able toachieve the nearly azimuthal polarization state in the lens aperturewhile suppressing the loss of light quantity, based on the simpleconfiguration, through collaboration of the birefringent element 21 andthe optical rotator 22 as the fourth modification example was.

FIG. 17 is a drawing schematically showing a major configuration of anexposure apparatus according to a sixth modification example of thepresent embodiment. In the sixth modification example the configurationfrom the mask blind 13 to the mask M is similar to that in the fourthmodification example of FIG. 15. However, the sixth modification exampleis different from the fourth modification example of FIG. 15 in that thebirefringent element 21 and the optical rotator 22 both are located atpredetermined positions in the optical path of the projection opticalsystem PL.

Namely, in the sixth modification example the birefringent element 21 islocated at a position optically conjugate with the mask M (i.e., at aposition where a secondary image of mask M is formed) or in a nearlytelecentric optical path near the conjugate position, in an optical pathbetween a second imaging optical system G2 and a third imaging opticalsystem G3. Furthermore, the optical rotator 22 is located at a positionrelatively close to the wafer W in an optical path of the third imagingoptical system G3 of the projection optical system PL, e.g., at aposition where the light beam is incident with variation of not morethan 10° in the angle of incidence. As a result, the sixth modificationexample is also able to achieve the nearly azimuthal polarization statein the lens aperture while suppressing the loss of light quantity, basedon the simple configuration, through collaboration of the birefringentelement 21 and the optical rotator 22 as the fourth modification examplewas. In the sixth modification example the birefringent element 21 islocated in the optical path on the wafer W side with respect to theoptical path folding mirror in the projection optical system PL. In thecase of this configuration, even if there occurs a phase difference dueto reflection between the p-polarization and the s-polarization for theoptical path folding mirror, the polarization state after the reflectioncan be nearly circular polarization when the polarization stateimpinging upon the optical path folding mirror is elliptic polarization.Therefore, the sixth modification example is more preferably adoptedthan the aforementioned fifth modification example in the case where theoptical path folding mirror is located in the projection optical system.

In the embodiment of FIG. 5 and in the first modification example to thesixth modification example, the birefringent element 21 is an opticallytransparent member made of a uniaxial crystal, for example, like rockcrystal or a pair of optically transparent members made of a crystalmaterial of the cubic system, for example, like fluorite. However, thebirefringent element does not have to be limited to those, but thebirefringent element can also be an optically transparent member withinternal stress substantially with rotational symmetry with respect tothe optical axis, e.g., an optically transparent member like aplane-parallel plate of silica.

In this case, when a light beam of plane waves in a substantiallycircular polarization state is made incident to the birefringent elementconsisting of the optically transparent member with internal stresssubstantially which is rotational symmetry with respect to the opticalaxis, the polarization distribution in the lens aperture as shown inFIG. 10 (a) or (b) can be obtained. For making the polarizationdistribution in the lens aperture approximately uniform in the plane,the birefringent element consisting of the optically transparent memberwith internal stress is preferably located near the pupil of the opticalsystem (in the embodiment of FIG. 5, for example, a position near thepupil of the imaging optical system 14 and closer to the light sourcethan the optical rotator 21). Concerning the details of a method ofproviding the optically transparent member, for example, like theplane-parallel plate of silica with the substantially rotationallysymmetric internal stress (to provide the member with a desiredbirefringence distribution), reference can be made, for example, toInternational Application Published under PCT WO03/007045.

In the embodiment of FIG. 5 and in the first modification example to thesixth modification example, the nearly azimuthal polarization state inthe lens aperture is achieved through collaboration of the two elementsdisposed with a spacing, i.e., the birefringent element 21 and theoptical rotator 22. However, the nearly azimuthal polarization state inthe lens aperture can also be achieved by using a birefringent opticalrotator which is made of an optical material with linear birefringenceand optical rotatory power and the optic axis of which is arrangedsubstantially in parallel with the optical axis, e.g., a birefringentoptical rotator consisting of an optically transparent member of aplane-parallel plate shape made of rock crystal, and making a light beamin a substantially circular polarization state incident to thebirefringent optical rotator.

In this case, the birefringent optical rotator is located at a positionwhere a light beam of substantially spherical waves is incident thereto,and has a required thickness for converting a light beam in a peripheralregion of incident light into a light beam in a substantially linearpolarization state of approximately circumferential vibration in thelens aperture. Namely, the relationship between the thickness of thebirefringent optical rotator and angles of incident rays is so set thatcircularly polarized rays incident to the peripheral region of thebirefringent optical rotator are converted into linearly polarized lightby birefringence and that their polarization is rotated by 45° byoptical rotatory power.

The change of polarization in the birefringent optical rotator will bedescribed below with reference to the Poincare sphere shown in FIG. 18.In FIG. 18, S₁, S₂, and S₃ are the Stokes parameters to indicate apolarization state. In the birefringent optical rotator, light incidentin a perfectly circular polarization state corresponding to point A(0,0,1) is subject to rotational action around the S₁ axis due to thebirefringence and subject to rotational action around the S₃ axis due tothe optical rotatory power, to reach a azimuthal polarization statecorresponding to point B (1,0,0).

Incidentally, in the case of the aforementioned birefringent element 21,the light incident in a perfectly circular polarization statecorresponding to point A (0,0,1) is subject to only rotational actionaround the S₁ axis due to the birefringence, to reach point B′ (0,1,0).For adjusting the amount of the rotation and the amount of thebirefringence in the birefringent optical rotator, the birefringentoptical rotator is preferably comprised of a first optically transparentmember made of an optical material with clockwise optical rotatory power(e.g., right-handed rock crystal), and a second optically transparentmember made of an optical material with counterclockwise opticalrotatory power (e.g., left-handed rock crystal).

FIG. 19 is a drawing schematically showing a major configuration of anexposure apparatus according to a seventh modification example of thepresent embodiment. In the seventh modification example theconfiguration from the mask blind 13 to the mask M is similar to that inthe embodiment shown in FIG. 5. However, the seventh modificationexample is different from the embodiment shown in FIG. 5, in that thebirefringent element 21 and the optical rotator 22 are replaced by abirefringent optical rotator 23 disposed in the optical path between themask blind 13 and the imaging optical system 14.

Namely, in the seventh modification example the birefringent opticalrotator 23 is located in the nearly telecentric optical path near themask blind 13 located at the position optically conjugate with the maskM being a surface to be illuminated, in the optical path of theillumination optical system (2-14). As a result, the seventhmodification example is also able to achieve the nearly azimuthalpolarization state in the lens aperture while suppressing the loss oflight quantity, based on the simple configuration, through the action ofthe birefringent optical rotator 23 as the embodiment of FIG. 5 was.

FIG. 20 is a drawing schematically showing a major configuration of anexposure apparatus according to an eighth modification example of thepresent embodiment. In the eighth modification example the configurationfrom the mask blind 13 to the mask M is similar to that in the seventhmodification example of FIG. 19. However, the eighth modificationexample is different from the seventh modification example in that thebirefringent optical rotator 23 is located in the optical path betweenthe imaging optical system 14 and the mask M. Namely, in the eighthmodification example the birefringent optical rotator 23 is located inthe nearly telecentric optical path near the mask M, in the optical pathof the illumination optical system (2-14). As a result, the eighthmodification example is also able to achieve the nearly azimuthalpolarization state in the lens aperture while suppressing the loss oflight quantity, based on the simple configuration, through the action ofthe birefringent optical rotator 23 as the seventh modification examplewas.

FIG. 21 is a drawing schematically showing a major configuration of anexposure apparatus according to a ninth modification example of thepresent embodiment. In the ninth modification example the configurationfrom the mask blind 13 to the mask M is similar to that in the seventhmodification example of FIG. 19. However, the ninth modification exampleis different from the seventh modification example in that thebirefringent optical rotator 23 is located in the optical path betweenthe mask M and the projection optical system PL. Namely, in the ninthmodification example the birefringent optical rotator 23 is located inthe nearly telecentric optical path near the mask M (i.e., in theoptical path nearly telecentric on the mask M side), in the optical pathof the projection optical system PL. As a result, the ninth modificationexample is also able to achieve the nearly azimuthal polarization statein the lens aperture while suppressing the loss of light quantity, basedon the simple configuration, through the action of the birefringentoptical rotator 23 as the seventh modification example was.

FIG. 22 is a drawing schematically showing a major configuration of anexposure apparatus according to a tenth modification example of thepresent embodiment. In the tenth modification example the configurationfrom the mask blind 13 to the mask M is similar to that in the seventhmodification example of FIG. 19. However, the tenth modification exampleis different from the seventh modification example in that thebirefringent optical rotator 23 is located in the optical path betweenthe projection optical system PL and the wafer W. Namely, in the tenthmodification example the birefringent optical rotator 23 is located inthe nearly telecentric optical path near the wafer W (i.e., in theoptical path nearly telecentric on the wafer W side), in the opticalpath of the projection optical system PL. As a result, the tenthmodification example is also able to achieve the nearly azimuthalpolarization state in the lens aperture while suppressing the loss oflight quantity, based on the simple configuration, through the action ofthe birefringent optical rotator 23 as the seventh modification examplewas.

FIG. 23 is a drawing schematically showing a major configuration of anexposure apparatus according to an eleventh modification example of thepresent embodiment. In the eleventh modification example theconfiguration from the mask blind 13 to the mask M is similar to that inthe fourth modification example of FIG. 15. However, the eleventhmodification example is different from the fourth modification examplein that the birefringent element 21 and the optical rotator 22 arereplaced by a birefringent optical rotator 23 located in the opticalpath between the imaging optical system 14 and the mask M. Namely, inthe eleventh modification example the birefringent optical rotator 23 islocated in the nearly telecentric optical path near the mask M, in theoptical path of the illumination optical system (2-14). As a result, theeleventh modification example is also able to achieve the nearlyazimuthal polarization state in the lens aperture while suppressing theloss of light quantity, based on the simple configuration, through theaction of the birefringent optical rotator 23 as the fourth modificationexample was.

FIG. 24 is a drawing schematically showing a major configuration of anexposure apparatus according to a twelfth modification example of thepresent embodiment. In the twelfth modification example theconfiguration from the mask blind 13 to the mask M is similar to that inthe eleventh modification example of FIG. 23. However, the twelfthmodification example is different from the eleventh modification examplein that the birefringent optical rotator 23 is located in the opticalpath between the imaging optical system 14 and the mask M. Namely, inthe eleventh modification example the birefringent optical rotator 23 islocated at a position optically conjugate with the mask M (a positionwhere a secondary image of mask M is formed) or in a nearly telecentricoptical path near the conjugate position, in the optical path betweenthe second imaging optical system G2 and the third imaging opticalsystem G3. As a result, the twelfth modification example is also able toachieve the nearly azimuthal polarization state in the lens aperturewhile suppressing the loss of light quantity, based on the simpleconfiguration, through the action of the birefringent optical rotator 23as the eleventh modification example was.

FIG. 25 is a drawing schematically showing a major configuration of anexposure apparatus according to a thirteenth modification example of thepresent embodiment. In the thirteenth modification example theconfiguration from the mask blind 13 to the mask M is similar to that inthe eleventh modification example of FIG. 23. However, the thirteenthmodification example is different from the eleventh modification examplein that the birefringent optical rotator 23 is located in the opticalpath between the projection optical system PL and the wafer W. Namely,in the thirteenth modification example the birefringent optical rotator23 is located in a nearly telecentric optical path near the wafer W(i.e., in an optical path nearly telecentric on the wafer W side), inthe optical path of the projection optical system PL. As a result, thethirteenth modification example is also able to achieve the nearlyazimuthal polarization state in the lens aperture while suppressing theloss of light quantity, based on the simple configuration, through theaction of the birefringent optical rotator 23 as the eleventhmodification example was. In the twelfth modification example and thethirteenth modification example, the birefringent optical rotator 23 islocated in the optical path on the wafer W side with respect to theoptical path folding mirror in the projection optical system PL. In thecase of this configuration, as in the case of the aforementioned sixthmodification example, even if there occurs a phase difference due toreflection between the p-polarization and the s-polarization for theoptical path folding mirror, the polarization state after the reflectioncan be nearly circular polarization when the polarization stateimpinging upon the optical path folding mirror is set to ellipticpolarization. Therefore, the thirteenth modification example is morepreferably adopted than the aforementioned eleventh modification examplein the case where the optical path folding mirror is located in theprojection optical system.

FIG. 26 is a drawing schematically showing a major configuration of anexposure apparatus according to a fourteenth modification example of thepresent embodiment. In the fourteenth modification example theconfiguration from the mask blind 13 to the mask M is similar to that inthe embodiment shown in FIG. 25. However, the fourteenth modificationexample is different from the exposure apparatus of the embodiment ofFIG. 25 in that, while the mask M is illuminated by circularly polarizedlight in the exposure apparatus of the embodiment of FIG. 25, the mask Mis illuminated by linearly polarized light in the exposure apparatus ofthe fourteenth modification example and in that, while the projectionoptical system PL of the embodiment of FIG. 25 is a catadioptric opticalsystem of the threefold imaging type including the concave mirror CM andtwo optical path folding mirrors, the projection optical system PL ofthe fourteenth modification example is a catadioptric optical system ofa twofold imaging type including a concave mirror CM, a polarizationbeam splitter PBS, and one optical path folding mirror FM.

In FIG. 26, the projection optical system PL in the fourteenthmodification example is an optical system telecentric on the mask M sideand on the wafer W side, and is comprised of a first imaging opticalsystem G1 for forming an intermediate image of mask M and a secondimaging optical system G2 for forming an image of this intermediateimage on a wafer W as a photosensitive substrate.

The first imaging optical system G1 is comprised of a first lens unitlocated nearest to the mask side (mask-side field lens unit), apolarization beam splitter PBS for reflecting a light beam of linearlypolarized light having passed through the first lens unit, a firstquarter-wave plate QW1 for converting the light beam of linearlypolarized light reflected by the polarization beam splitter PBS, into alight beam of circularly polarized light, a concave mirror CM forreflecting the light beam having passed through the first quarter-waveplate QW1, a negative lens unit located in the optical path between theconcave mirror CM and the first quarter-wave plate QW1, a secondquarter-wave plate QW2 for converting the light beam of linearlypolarized light transmitted via the negative lens unit and the firstquarter-wave plate by the polarization beam splitter PBS, into a lightbeam of circularly polarized light, a optical path folding mirror FM fordeflecting the optical path of the light beam from the polarization beamsplitter PBS by about 90°, and a positive lens unit located between thepolarization beam splitter PBS and the intermediate image point(intermediate-image-side field lens unit). This intermediate-image-sidefield lens unit keeps the optical path on the intermediate image side ofthe first imaging optical system G1 (the optical path between the firstimaging optical system G1 and the second imaging optical system G2)approximately telecentric.

The second imaging optical system G2 has a structure similar to therefracting projection optical system PL in the fourth modificationexample shown in FIG. 14, in which the birefringent element 21 islocated in the optical path between the second imaging optical system G2and the intermediate image point and in which the optical rotator 22 islocated at a predetermined position in the optical path of the secondimaging optical system G2, preferably, at a position near an aperturestop AS.

Then the linearly polarized light from the mask M passes through thefirst lens unit, is then reflected by the polarization beam splitterPBS, and thereafter travels through the first quarter-wave plate QW1 tobe converted into circularly polarized light, and the circularlypolarized light travels through the negative lens unit to reach theconcave mirror CM. The light beam of circularly polarized lightreflected by the concave mirror CM travels again through the negativelens unit, and then passes through the first quarter-wave plate QW1 tobe converted into linearly polarized light, and the linearly polarizedlight passes through the polarization beam splitter PBS to reach thesecond quarter-wave plate QW2. This light beam is converted intolinearly polarized light by the second quarter-wave plate QW2, and thenthe linearly polarized light is reflected by the optical path foldingmirror FM and travels through the positive lens unit being theintermediate-image-side field lens unit, to form an intermediate imageof the mask M. Light from this intermediate image then travels throughthe birefringent element 21 to be incident to the second imaging opticalsystem G2, and thereafter passes through the optical rotator 22 in thissecond imaging optical system G2 to form a reduced image as a secondaryimage of the mask M on the image plane. This reduced image is a mirrorimage of the mask M (which is an image having a negative lateralmagnification in the direction in the plane of the drawing and apositive lateral magnification in the direction normal to the plane ofthe drawing).

In the fourteenth modification example the birefringent element 21 islocated in the nearly telecentric optical path near the intermediateimage point, in the optical path of the projection optical system PL.Furthermore, the optical rotator 22 is located near the pupil positionof the projection optical system PL. As a result, the fourteenthmodification example is also able to achieve the nearly azimuthalpolarization state in the lens aperture while suppressing the loss oflight quantity, based on the simple configuration, through collaborationof the birefringent element 21 and the optical rotator 22 as theembodiment of FIG. 25 was.

In the fourteenth modification example, since the light beam incident tothe optical path folding mirror FM is linearly polarized light ofp-polarization or s-polarization for the reflecting surface of theoptical path folding mirror FM, it becomes feasible to reduce influenceof phase jump on the reflecting surface of the optical path foldingmirror FM. In the fourteenth modification example, the illuminationoptical system may be arranged to illuminate the mask M with circularlypolarized light and in this case, a third quarter-wave plate is locatedin the optical path between the mask M and the polarization beamsplitter PBS in the projection optical system PL so as to guide linearlypolarized light to the polarization beam splitter. In the fourteenthmodification example the polarization beam splitter PBS is arranged toreflect the light beam from the mask M, but the polarization beamsplitter PBS may be arranged to transmit the light beam from the mask M(so that the optical system from the mask M to the concave mirror CM isaligned on a straight line).

FIG. 27 is a drawing schematically showing a major configuration of anexposure apparatus according to a fifteenth modification example of thepresent embodiment. In the fifteenth modification example theconfiguration from the mask blind 13 to the mask M and the configurationfrom the intermediate image point to the wafer W are similar to those inthe embodiment (fourteenth modification example) shown in FIG. 26.However, the fifteenth modification example is different from thefourteenth modification example in that, while the projection opticalsystem PL of the fourteenth modification example is arranged to guidethe light beam from the mask M to the wafer W while reflecting it threetimes, the projection optical system PL of the fifteenth modificationexample is arranged to guide the light beam from the mask M to the waferW while reflecting it four times.

In FIG. 27, the projection optical system PL in the fifteenthmodification example is an optical system telecentric on the mask M sideand on the wafer W side as the projection optical system PL in thefourteenth modification example was, and is comprised of a first imagingoptical system G1 for forming an intermediate image of the mask M, and asecond imaging optical system G2 for forming an image of thisintermediate image on the wafer W as a photosensitive substrate.

The first imaging optical system G1 is comprised of a first lens unitlocated nearest to the mask side (mask-side field lens unit), apolarization beam splitter PBS having a first polarization splittingsurface PBS1 for reflecting a light beam of linearly polarized lighthaving passed through the first lens unit, a first quarter-wave plateQW1 for converting the light beam of linearly polarized light reflectedby the first polarization splitting surface PBS1, into a light beam ofcircularly polarized light, a concave mirror CM for reflecting the lightbeam having passed through the first quarter-wave plate QW1, a negativelens unit located in the optical path between the concave mirror CM andthe first quarter-wave plate QW1, a second polarization splittingsurface PBS2 for transmitting a light beam of linearly polarized lighttransmitted via the negative lens unit and the first quarter-wave plateby the first polarization splitting surface PBS1, a second quarter-waveplate QW2 for converting the light beam of linearly polarized lighttransmitted by the second polarization splitting surface PBS2, into alight beam of circularly polarized light, a return mirror RM having areflecting plane for returning the light beam of circularly polarizedlight from the second quarter-wave plate QW2, a third quarter-wave plateQW3 for converting a light beam of linearly polarized light reflected bythe second polarization splitting surface PBS2 after the round-trippassage through the second quarter-wave plate QW2, into a light beam ofcircularly polarized light, and a positive lens unit(intermediate-image-side field lens unit) located between the secondpolarization splitting surface PBS2 and the intermediate image point.This intermediate-image-side field lens unit keeps the optical path onthe intermediate image side of the first imaging optical system G1 (theoptical path between the first imaging optical system G1 and the secondimaging optical system G2) nearly telecentric.

The second imaging optical system G2 has a structure similar to therefracting projection optical system PL in the fourteenth modificationexample shown in FIG. 26, in which the birefringent element 21 islocated in the optical path between the second imaging optical system G2and the intermediate image point and in which the optical rotator 22 islocated at a predetermined position in the optical path of the secondimaging optical system G2, preferably, at a position near an aperturestop AS.

The light beam of linearly polarized light from the mask M travelsthrough the first lens unit, is then reflected by the first polarizationsplitting surface PBS1 of the polarization beam splitter PBS, and thentravels through the first quarter-wave plate QW1 to be converted intocircularly polarized light, and the circularly polarized light travelsthrough the negative lens unit to reach the concave mirror CM. The lightbeam of circularly polarized light reflected by the concave mirror CMtravels again through the negative lens unit and thereafter passesthrough the first quarter-wave plate QW1 to be converted into linearlypolarized light. The linearly polarized light passes through the firstpolarization splitting surface PBS1 and the second polarizationsplitting surface PBS2 of the polarization beam splitter PBS to reachthe second quarter-wave plate QW2. This light beam is converted intocircularly polarized light by the second quarter-wave plate QW2, and thecircularly polarized light then reaches the return mirror RM. The lightbeam of circularly polarized light reflected by the return mirror RMtravels through the second quarter-wave plate QW2 to be converted intolinearly polarized light, and then the linearly polarized light isreflected by the second polarization splitting surface PBS2 of thepolarization beam splitter PBS to reach the third quarter-wave plateQW3. The light beam of linearly polarized light incident to the thirdquarter-wave plate QW3 is converted into a light beam of circularlypolarized light by this third quarter-wave plate QW3, and the light beamof circularly polarized light then travels through the positive lensunit being the intermediate-image-side field lens unit, to form anintermediate image of the mask M. Light from this intermediate imagetravels through the birefringent element 21 to be incident to the secondimaging optical system G2, and then passes through the optical rotatorin this second imaging optical system G2 to form a reduced image as asecondary image of the mask M on the image plane. This reduced image isa front image of the mask M (an image having a positive lateralmagnification in the direction in the plane of the drawing and apositive lateral magnification in the direction perpendicular to theplane of the drawing, i.e., an erect image).

In the fifteenth modification example the birefringent element 21 isalso located in the nearly telecentric optical path near theintermediate image point, in the optical path of the projection opticalsystem PL. Furthermore, the optical rotator 22 is located near the pupilposition of the projection optical system PL. As a result, the fifteenthmodification example is able to achieve the nearly azimuthalpolarization state in the lens aperture while suppressing the loss oflight quantity, based on the simple configuration, through collaborationof the birefringent element 21 and the optical rotator 22 as theembodiment of FIG. 26 was.

In the fifteenth modification example the illumination optical systemmay be arranged to illuminate the mask M with circularly polarized lightand in this case, the third quarter-wave plate may be located in theoptical path between the mask M and the polarization beam splitter PBSin the projection optical system PL so as to guide linearly polarizedlight to the polarization beam splitter PBS. The fifteenth modificationexample is arranged to reflect the light beam from the mask M by thefirst polarization splitting surface PBS1 of the polarization beamsplitter PBS, but the optical system may be arranged so that the lightbeam from the mask M is transmitted by the first polarization splittingsurface PBS1 (so that the optical system from the mask M to the concavemirror CM is aligned on a straight line). In the fifteenth modificationexample the second polarization splitting surface PBS2 of thepolarization beam splitter PBS is arranged to reflect the light beamfrom the return mirror RM, but the optical system may also be arrangedso that the second polarization splitting surface PBS2 transmits thelight beam from the return mirror (so that the optical system from thereturn mirror RM to the wafer W is aligned on a straight line). At thistime, the light beam from the first polarization splitting surface PBS1is reflected by the second polarization splitting surface PBS2.

The following controls may be properly performed according to the shapeof the pattern as an exposed object on the mask M: the control of thepolarization state by the polarization state converter 4, the control ofthe exchange operation of the diffractive optical element, and thecontrol of the operation of the axicon system 8 as an annular ratiochanging means as described above. It is contemplated in theabove-described embodiment and modification examples that when thepolarization state is set to the linear polarization state or theunpolarized state through the action of the polarization state converter4, the polarization state is affected by the birefringent element 21 orthe birefringent optical rotator 23 disposed in the optical path betweenthe mask M and the wafer W. In that case, the birefringent element 21 orthe birefringent optical rotator 23 may be retracted from the opticalpath, or the birefringent element 21 or the birefringent optical rotator23 may be replaced with an optically transparent member withoutbirefringence (e.g., a plane-parallel plate made of silica or the like)as occasion may demand. Such retracting operation or replacing operationof the birefringent element 21 or the birefringent optical rotator 23may also be controlled in synchronism with the aforementioned controls.

The exposure apparatus of the aforementioned embodiment can be used tofabricate micro devices (semiconductor devices, image pickup devices,liquid-crystal display devices, thin-film magnetic heads, etc.) byilluminating a mask (reticle) by the illumination optical apparatus(illumination step) and projecting a pattern to be transferred, formedin the mask, onto a photosensitive substrate with the projection opticalsystem (exposure step). An example of a technique of forming apredetermined circuit pattern in a wafer or the like as a photosensitivesubstrate with the exposure apparatus of the aforementioned embodimentto obtain semiconductor devices as micro devices will be described belowwith reference to the flowchart of FIG. 28.

The first step 301 in FIG. 28 is to deposit a metal film on each waferin one lot. The next step 302 is to apply a photoresist onto the metalfilm on each wafer in the lot. The subsequent step 303 is tosequentially transfer an image of a pattern on the mask into each shotarea on each wafer in the lot through the projection optical system,using the exposure apparatus of the aforementioned embodiment. Thesubsequent step 304 is to perform development of the photoresist on eachwafer in the lot and the subsequent step 305 is to perform etching oneach wafer in the lot, using the resist pattern as a mask and thereby toform a circuit pattern corresponding to the pattern on the mask, in eachshot area on each wafer. Subsequent steps include formation of circuitpatterns in upper layers, and others, thereby fabricating devices suchas semiconductor devices. The above-described semiconductor devicefabrication method permits us to obtain semiconductor devices withextremely fine circuit patterns at high throughput.

The exposure apparatus of the aforementioned embodiment can also be usedto fabricate a liquid-crystal display device as a micro device byforming predetermined patterns (circuit pattern, electrode pattern,etc.) on plates (glass substrates). An example of a technique forfabricating the liquid-crystal display device will be described belowwith reference to the flowchart of FIG. 29. In FIG. 29, a patternforming step 401 is to execute a so-called photolithography step totransfer a pattern of a mask onto a photosensitive substrate (glasssubstrate coated with a resist, or the like) with the exposure apparatusof the aforementioned embodiment. This photolithography step results informing the predetermined pattern including a number of electrodes andothers on the photosensitive substrate. Thereafter, the exposedsubstrate is subjected to each of steps such as development, etching,and resist removal, whereby a predetermined pattern is formed on thesubstrate. Thereafter, the process transfers to next color filterforming step 402.

The next color filter forming step 402 is to form a color filter inwhich a number of sets of three dots corresponding to R (Red), G(Green), and B (Blue) are arrayed in a matrix pattern, or in which setsof three stripe filters of R, G, and B are arrayed as a plurality oflines along the horizontal scan line direction. After completion of thecolor filter forming step 402, a cell assembling step 403 is carriedout. The cell assembling step 403 is to assemble a liquid crystal panel(liquid crystal cell), using the substrate with the predeterminedpattern obtained in the pattern forming step 401, the color filterobtained in the color filter forming step 402, and so on.

In the cell assembling step 403, for example, a liquid crystal is pouredinto between the substrate with the predetermined pattern obtained inthe pattern forming step 401 and the color filter obtained in the colorfilter forming step 402, to fabricate a liquid crystal panel (liquidcrystal cell). The subsequent module assembling step 404 is to installeach of components such as an electric circuit, a backlight, etc. fordisplay operation of the assembled liquid crystal panel (liquid crystalcell) to complete the liquid-crystal display device. The above-describedmethod of fabricating the liquid-crystal display device permits us toobtain the liquid-crystal display device with an extremely fine circuitpattern at high throughput.

In the aforementioned embodiment the exposure light was the KrF excimerlaser light (wavelength: 248 nm) or the ArF excimer laser light(wavelength: 193 nm), but, without having to be limited to this, thepresent invention can also be applied to the other appropriate laserlight sources, e.g., an F₂ laser light source for supplying laser lightof wavelength of 157 nm. Furthermore, the aforementioned embodimentdescribed the present invention with the example of the exposureapparatus provided with the illumination optical apparatus, but it isapparent that the present invention can be applied to the ordinaryillumination optical apparatus for illuminating a surface to beilluminated, except for the masks and wafers.

In the aforementioned embodiment, it is also possible to adopt atechnique of filling the optical path between the projection opticalsystem and the photosensitive substrate with a medium having therefractive index of more than 1.1 (typically, a liquid), i.e., theso-called liquid immersion method. When the liquid fills the spacebetween the projection optical system and the photosensitive materialsuch as the resist applied on the surface of the photosensitivesubstrate, the transmittance on the resist surface becomes higher fordiffracted light of the s-polarization component (TE polarizationcomponent) contributing to improvement in contrast than when air (gas)fills the space between the projection optical system and the resistapplied on the surface of the photosensitive substrate; therefore, highimaging performance can be achieved even if the numerical aperture NA ofthe projection optical system is over 1.0. In this case, the techniqueof filling the liquid in the optical path between the projection opticalsystem and the photosensitive substrate can be one selected from themethod of locally filling the space with the liquid as disclosed inInternational Publication WO99/49504, the method of moving a stageholding a substrate as an exposed object, in a liquid bath as disclosedin Japanese Patent Application Laid-Open No. 6-124873, the method offorming a liquid bath of a predetermined depth on a stage and holding asubstrate in the liquid bath as disclosed in Japanese Patent ApplicationLaid-Open No. 10-303114, and soon.

The liquid is preferably one that is transparent to exposure light, thathas the refractive index as high as possible, and that is stable againstthe projection optical system and the photoresist applied on the surfaceof the substrate; for example, where the KrF excimer laser light or theArF excimer laser light is used as exposure light, the liquid can bepure water or deionized water. Where the exposure light is the F₂ laserlight, the liquid can be a fluorine-based liquid, for example, such asfluorine oil or perfluoro polyether (PFPE) capable of transmitting theF₂ laser light. The present invention is also applicable to twin-stagetype exposure apparatus. The structure and exposure operation of thetwin-stage type exposure apparatus are disclosed, for example, inJapanese Patent Applications Laid-Open No. 10-163099 and Laid-Open No.10-214783 (corresponding to U.S. Pats. No. 6,341,007, U.S. Pat. No.6,400,441, U.S. Pat. No. 6,549,269, and U.S. Pat. No. 6,590,634),Published Japanese translation of PCT Application No. 2000-505958(corresponding to U.S. Pat. No. 5,969,441), or U.S. Pat. No. 6,208,407.

DESCRIPTION OF REFERENCE SYMBOLS

-   -   1 light source    -   4 polarization state converter    -   4 a quarter-wave plate    -   4 b half-wave plate    -   4 c depolarizer    -   5, 50 diffractive optical element (light beam converter)    -   6 afocal lens    -   8 conical axicon system    -   9 zoom lens    -   10 micro fly's eye lens    -   11 polarization monitor    -   11 a beam splitter    -   12 condenser optical system    -   13 mask blind    -   14 imaging optical system    -   21 birefringent element    -   22 optical rotator    -   23 birefringent optical rotator    -   M mask    -   PL projection optical system    -   W wafer

1-29. (canceled)
 30. An optical system comprising: a birefringentelement, disposed in an optical path of the optical system, thatachieves a substantially circumferential distribution or a substantiallyradial distribution as a fast axis distribution in a lens aperture; andan optical rotator disposed behind the birefringent element and adaptedto rotate a polarization state in the lens aperture.
 31. The opticalsystem according to claim 30, wherein the birefringent element includesan optically transparent member which is made of a uniaxial crystalmaterial and a crystallographic axis of which is arranged substantiallyin parallel with an optical axis of the optical system, and wherein abeam bundle of substantially spherical waves in a substantially circularpolarization state is incident to the optically transparent member. 32.The optical system according to claim 30, wherein the birefringentelement includes at least a pair of optically transparent members madeof a crystal material of the cubic system, wherein the pair of opticallytransparent members are so positioned as to achieve the substantiallycircumferential distribution or the substantially radial distribution asthe fast axis distribution in the lens aperture, and wherein a beambundle of substantially spherical waves in a substantially circularpolarization state is incident to the pair of optically transparentmembers.
 33. The optical system according to claim 32, wherein the pairof optically transparent members are arranged in a state in which acrystal orientation <111> is substantially parallel with an optical axisof the optical system and in which the other crystal orientations arerelatively rotated by about 60° around the optical axis.
 34. The opticalsystem according to claim 32, wherein the pair of optically transparentmembers are arranged in a state in which a crystal orientation <100> issubstantially parallel with an optical axis of the optical system and inwhich the other crystal orientations are relatively rotated by about 45°around the optical axis.
 35. The optical system according to claim 30,wherein the birefringent element includes an optically transparentmember which is located near a pupil of the optical system and whichincludes internal stress substantially with rotational symmetry withrespect to an optical axis of the optical system, and wherein a beambundle in a substantially circular polarization state is incident to theoptically transparent member.
 36. The optical system according to claim30, wherein the optical rotator is located at a position where a beambundle is incident thereto with variation of not more than 10° in anangle of incidence.
 37. The optical system according to claim 30,wherein the optical rotator rotates the polarization state in the lensaperture by about 45°.
 38. The optical system according to claim 30,said optical system including a projection optical system which forms animage of a first plane on a second plane.
 39. The optical systemaccording to claim 38, wherein the projection optical system is arrangedto be substantially telecentric on the first plane side, and wherein thebirefringent element is located in an optical path which issubstantially telecentric on the first plane side.
 40. The opticalsystem according to claim 30, said optical system including anillumination optical system which illuminates a surface to beilluminated, in a substantially telecentric manner.
 41. The opticalsystem according to claim 40, wherein the birefringent element islocated at or near a position optically conjugate with the surface to beilluminated, in an optical path of the illumination optical system. 42.The optical system according to claim 40, wherein the illuminationoptical system forms a secondary light source including a predeterminedoptical intensity distribution, on an illumination pupil plane, andwherein the predetermined optical intensity distribution of thesecondary light source is so set that an optical intensity in a pupilcenter region being a region on the illumination pupil and including anoptical axis is smaller than an optical intensity in a region around thepupil center region.
 43. The optical system according to claim 42,wherein the predetermined optical intensity distribution of thesecondary light source includes an optical intensity distribution of anannular shape or multi-pole shape.
 44. The optical system according toclaim 30, said optical system including an illumination optical systemwhich illuminates a first plane in a substantially telecentric manner;and a projection optical system which forms an image of the first planeon a second plane.
 45. The optical system according to claim 44, whereinthe birefringent element is located in an optical path of theillumination optical system, and wherein the optical rotator is locatedin an optical path of the projection optical system.
 46. The opticalsystem according to claim 45, wherein the birefringent element islocated near the first plane, or at or near a position opticallyconjugate with the first plane, in the optical path of the illuminationoptical system.
 47. The optical system according to claim 46, whereinthe illumination optical system forms a secondary light source includinga predetermined optical intensity distribution, on an illumination pupilplane, and wherein the predetermined optical intensity distribution ofthe secondary light source is so set that an optical intensity in apupil center region being a region on the illumination pupil andincluding an optical axis is smaller than an optical intensity in aregion around the pupil center region.
 48. The optical system accordingto claim 47, wherein the predetermined optical intensity distribution ofthe secondary light source includes an optical intensity distribution ofan annular shape or multi-pole shape.
 49. The optical system accordingto claim 30, said optical system being an optical system forlithography.
 50. An optical system comprising: a birefringent opticalrotator which is made of an optical material with linear birefringenceand optical rotatory power and an optic axis of which is arrangedsubstantially in parallel with an optical axis of the optical system,wherein a beam bundle in a substantially circular polarization state isincident to the birefringent optical rotator.
 51. The optical systemaccording to claim 50, wherein the birefringent optical rotator islocated at a position where a beam bundle of substantially sphericalwaves is incident thereto, and includes a required thickness forconverting a beam bundle in a peripheral region of the incident beambundle into a beam bundle in a substantially linear polarization stateof substantially circumferential vibration in a lens aperture.
 52. Theoptical system according to claim 51, wherein the birefringent opticalrotator includes a first optically transparent member made of an opticalmaterial with clockwise optical rotatory power, and a second opticallytransparent member made of an optical material with counterclockwiseoptical rotatory power.
 53. The optical system according to claim 51,said optical system including a projection optical system which forms animage of a first plane on a second plane.
 54. The optical systemaccording to claim 53, wherein the projection optical system is arrangedto be substantially telecentric on the first plane side, and wherein thebirefringent optical rotator is located in an optical path which issubstantially telecentric on the first plane side.
 55. The opticalsystem according to claim 53, wherein the projection optical system isarranged to be substantially telecentric on the second plane side, andwherein the birefringent optical rotator is located in an optical pathwhich is substantially telecentric on the second plane side.
 56. Theoptical system according to claim 50, said optical system including anillumination optical system which illuminates a surface to beilluminated, in a substantially telecentric manner.
 57. The opticalsystem according to claim 56, wherein the birefringent optical rotatoris located near the surface to be illuminated, or at or near a positionoptically conjugate with the surface to be illuminated, in an opticalpath of the illumination optical system.
 58. The optical systemaccording to claim 57, wherein the illumination optical system forms asecondary light source including a predetermined optical intensitydistribution, on an illumination pupil plane, and wherein thepredetermined optical intensity distribution of the secondary lightsource is so set that an optical intensity in a pupil center regionbeing a region on the illumination pupil and including an optical axisis smaller than an optical intensity in a region around the pupil centerregion.
 59. The optical system according to claim 58, wherein thepredetermined optical intensity distribution of the secondary lightsource includes an optical intensity distribution of an annular shape ormulti-pole shape.
 60. The optical system according to claim 50, saidoptical system including a projection optical system which forms animage of a first plane on a second plane.
 61. The optical systemaccording to claim 60, wherein the projection optical system is arrangedto be substantially telecentric on the first plane side, and wherein thebirefringent optical rotator is located in an optical path which issubstantially telecentric on the first plane side.
 62. The opticalsystem according to claim 60, wherein the projection optical system isarranged to be substantially telecentric on the second plane side, andwherein the birefringent optical rotator is located in an optical pathwhich is substantially telecentric on the second plane side.
 63. Theoptical system according to claim 61, said optical system including anillumination optical system which illuminates a surface to beilluminated, in a substantially telecentric manner.
 64. The opticalsystem according to claim 63, wherein the birefringent optical rotatoris located near the surface to be illuminated, or at or near a positionoptically conjugate with the surface to be illuminated, in an opticalpath of the illumination optical system.
 65. The optical systemaccording to claim 64, wherein the illumination optical system forms asecondary light source including a predetermined optical intensitydistribution, on an illumination pupil plane, and wherein thepredetermined optical intensity distribution of the secondary lightsource is so set that an optical intensity in a pupil center regionbeing a region on the illumination pupil and including an optical axisis smaller than an optical intensity in a region around the pupil centerregion.
 66. The optical system according to claim 65, wherein thepredetermined optical intensity distribution of the secondary lightsource includes an optical intensity distribution of an annular shape ormulti-pole shape.
 67. The optical system according to claim 63, whereinthe illumination optical system forms a secondary light source includinga predetermined optical intensity distribution, on an illumination pupilplane, and wherein the predetermined optical intensity distribution ofthe secondary light source is so set that an optical intensity in apupil center region being a region on the illumination pupil andincluding an optical axis is smaller than an optical intensity in aregion around the pupil center region.
 68. The optical system accordingto claim 67, wherein the predetermined optical intensity distribution ofthe secondary light source includes an optical intensity distribution ofan annular shape or multi-pole shape.
 69. The optical system accordingto claim 50, said optical system being an optical system forlithography.
 70. An optical system comprising: a birefringent element;an optical rotator located in an optical path behind the birefringentelement; and an optical member located in an optical path between thebirefringent element and the optical rotator and including apredetermined power.
 71. The optical system according to claim 70,wherein the birefringent element includes an optically transparentmember which is made of a uniaxial crystal material and acrystallographic axis of which is arranged substantially in parallelwith an optical axis of the optical system.
 72. The optical systemaccording to claim 71, wherein a beam bundle of substantially sphericalwaves in a substantially circular polarization state is incident to theoptically transparent member.
 73. The optical system according to claim72, wherein the birefringent element achieves a substantiallycircumferential distribution or a substantially radial distribution as afast axis distribution in a lens aperture, and wherein the opticalrotator rotates a polarization state in the lens aperture.
 74. Theoptical system according to claim 70, wherein the birefringent elementincludes at least a pair of optically transparent members made of acrystal material of the cubic system; wherein the pair of opticallytransparent members are positioned so as to achieve the substantiallycircumferential distribution or the substantially radial distribution asthe fast axis distribution in the lens aperture, and wherein a beambundle of substantially spherical waves in a substantially circularpolarization state is incident to the pair of optically transparentmembers.
 75. The optical system according to claim 70, wherein thebirefringent element includes an optically transparent member locatednear a pupil of the optical system and including internal stresssubstantially with rotational symmetry with respect to an optical axisof the optical system, and wherein a beam bundle in a substantiallycircular polarization state is incident to the optically transparentmember.
 76. The optical system according to claim 70, wherein theoptical member including the predetermined power comprises a lens. 77.The optical system according to claim 70, said optical system includingan illumination optical system which illuminates a surface to beilluminated.
 78. The optical system according to claim 77, wherein thebirefringent element is located near the surface to be illuminated, orat or near a position optically conjugate with the surface to beilluminated, in an optical path of the illumination optical system, andwherein the optical member including the predetermined power includes animaging optical system which establishes the position opticallyconjugate with the surface to be illuminated.
 79. The optical systemaccording to claim 78, wherein the birefringent element is located at ornear the position optically conjugate with the surface to beilluminated, in the optical path of the illumination optical system, andwherein the optical rotator is located in the imaging optical system inthe illumination optical system.
 80. The optical system according toclaim 78, wherein the illumination optical system forms a secondarylight source including a predetermined optical intensity distribution,on an illumination pupil surface, and wherein the predetermined opticalintensity distribution of the secondary light source is so set that anoptical intensity in a pupil center region being a region on theillumination pupil and including an optical axis is smaller than anoptical intensity in a region around the pupil center region.
 81. Theoptical system according to claim 80, wherein the predetermined opticalintensity distribution of the secondary light source includes an opticalintensity distribution of an annular shape or multi-pole shape.
 82. Theoptical system according to claim 70, said optical system being anoptical system for lithography.
 83. An optical system including anoptical axis, comprising: a first optically transparent member which ismade of a uniaxial crystal material and a crystallographic axis of whichis arranged substantially in parallel with the optical axis; a secondoptically transparent member which is made of a uniaxial crystalmaterial and a crystallographic axis of which is arranged substantiallyin parallel with the optical axis; and an optical member located in anoptical path between the first optically transparent member and thesecond optically transparent member and including a predetermined power.84. The optical system according to claim 83, wherein the firstoptically transparent member is made of a material selected from rockcrystal, magnesium fluoride, and lithium aluminum calcium fluoride, andwherein the second optically transparent member is made of rock crystal.85. The optical system according to claim 83, wherein a beam bundle ofsubstantially spherical waves in a substantially circular polarizationstate is incident to the first optically transparent member.
 86. Theoptical system according to claim 85, wherein the first opticallytransparent member achieves a substantially circumferential distributionor a substantially radial distribution as a fast axis distribution in alens aperture, and wherein the second optically transparent memberrotates a polarization state in the lens aperture.
 87. The opticalsystem according to claim 83, wherein the optical member including thepredetermined power comprises a lens.
 88. The optical system accordingto claim 83, said optical system including an illumination opticalsystem which illuminates a surface to be illuminated.
 89. The opticalsystem according to claim 88, wherein the first optically transparentmember is located near the surface to be illuminated, or at or near aposition optically conjugate with the surface to be illuminated, in anoptical path of the illumination optical system, and wherein the opticalmember including the predetermined power includes an imaging opticalsystem which establishes the position optically conjugate with thesurface to be illuminated.
 90. The optical system according to claim 89,wherein the first optically transparent member is located at or near theposition optically conjugate with the surface to be illuminated, in theoptical path of the illumination optical system, and wherein the secondoptically transparent member is located in the imaging optical system inthe illumination optical system.
 91. The optical system according toclaim 89, wherein the illumination optical system forms a secondarylight source including a predetermined optical intensity distribution,on an illumination pupil surface, and wherein the predetermined opticalintensity distribution of the secondary light source is so set that anoptical intensity in a pupil center region being a region on theillumination pupil and including the optical axis is smaller than anoptical intensity in a region around the pupil center region.
 92. Theoptical system according to claim 91, wherein the predetermined opticalintensity distribution of the secondary light source includes an opticalintensity distribution of an annular shape or multi-pole shape.
 93. Theoptical system according to claim 83, said optical system being anoptical system for lithography.
 94. An exposure apparatus comprising: anoptical system which effects exposure of a predetermined pattern on aphotosensitive substrate, wherein said optical system comprises: abirefringent element which achieves a substantially circumferentialdistribution or a substantially radial distribution as a fast axisdistribution in a lens aperture; and an optical rotator located behindthe birefringent element and adapted to rotate a polarization state inthe lens aperture.
 95. The exposure apparatus according to claim 94,wherein the optical system includes an illumination optical system whichilluminates the predetermined pattern in a substantially telecentricmanner.
 96. The exposure apparatus according to claim 95, wherein thebirefringent element is located at or near a position opticallyconjugate with the surface to be illuminated, in an optical path of theillumination optical system.
 97. The exposure apparatus according toclaim 95, wherein the illumination optical system forms a secondarylight source including a predetermined optical intensity distribution,on an illumination pupil surface, and wherein the predetermined opticalintensity distribution of the secondary light source is so set that anoptical intensity in a pupil center region being a region on theillumination pupil and including the optical axis is smaller than anoptical intensity in a region around the pupil center region.
 98. Theexposure apparatus according to claim 97, wherein the predeterminedoptical intensity distribution of the secondary light source includes anoptical intensity distribution of an annular shape or multi-pole shape.99. The exposure apparatus according to claim 94, wherein the opticalsystem includes: an illumination optical system which illuminates thepredetermined pattern surface in a substantially telecentric manner; anda projection optical system which forms an image of the predeterminedpattern surface on a surface of a photosensitive substrate.
 100. Theexposure apparatus according to claim 99, wherein the birefringentelement is located in an optical path of the illumination opticalsystem, and wherein the optical rotator is located in an optical path ofthe projection optical system.
 101. The exposure apparatus according toclaim 100, wherein the birefringent element is located near a firstplane, or at or near a position optically conjugate with the firstplane, in the optical path of the illumination optical system.
 102. Theexposure apparatus according to claim 99, wherein the projection opticalsystem forms the image of the predetermined pattern surface on thesurface of the photosensitive substrate through a liquid.
 103. Anexposure apparatus comprising: an optical system which effects exposureof a predetermined pattern on a photosensitive substrate, wherein theoptical system comprises: a birefringent optical rotator which is madeof an optical material with linear birefringence and optical rotatorypower and an optic axis of which is arranged substantially in parallelwith an optical axis of the optical system, and wherein a beam bundle ina substantially circular polarization state is incident to thebirefringent optical rotator.
 104. The exposure apparatus according toclaim 103, wherein the birefringent optical rotator is located at aposition where a beam bundle of substantially spherical waves isincident thereto, and includes a required thickness for converting abeam bundle in a peripheral region of the incident beam bundle into abeam bundle in a substantially linear polarization state ofsubstantially circumferential vibration in a lens aperture.
 105. Theexposure apparatus according to claim 103 wherein the optical systemincludes an illumination optical system which illuminates thepredetermined pattern surface in a substantially telecentric manner.106. The exposure apparatus according to claim 105, wherein thebirefringent optical rotator is located near the predetermined patternsurface, or at or near a position optically conjugate with thepredetermined pattern surface, in an optical path of the illuminationoptical system.
 107. The exposure apparatus according to claim 106,wherein the illumination optical system forms a secondary light sourceincluding a predetermined optical intensity distribution, on anillumination pupil surface, and wherein the predetermined opticalintensity distribution of the secondary light source is so set that anoptical intensity in a pupil center region being a region on theillumination pupil and including the optical axis is smaller than anoptical intensity in a region around the pupil center region.
 108. Theexposure apparatus according to claim 107, wherein the predeterminedoptical intensity distribution of the secondary light source includes anoptical intensity distribution of an annular shape or multi-pole shape.109. The exposure apparatus according to claim 103, wherein the opticalsystem includes a projection optical system which forms an image of thepredetermined pattern surface on a surface of the photosensitivesubstrate.
 110. The exposure apparatus according to claim 109, whereinthe projection optical system is arranged to be substantiallytelecentric on the predetermined pattern surface side, and wherein thebirefringent optical rotator is located in an optical path which issubstantially telecentric on the predetermined pattern surface side.111. The exposure apparatus according to claim 109, wherein theprojection optical system is arranged to be substantially telecentric onthe photosensitive substrate surface side, and wherein the birefringentoptical rotator is located in an optical path which is substantiallytelecentric on the photosensitive substrate surface side.
 112. Theexposure apparatus according to claim 109, wherein the projectionoptical system forms the image of the predetermined pattern surface onthe surface of the photosensitive substrate through a liquid.
 113. Anexposure apparatus comprising: an optical system which effects exposureof a predetermined pattern on a photosensitive substrate, wherein theoptical system comprises: a birefringent element; an optical rotatorlocated in an optical path behind the birefringent element; and anoptical member located in an optical path between the birefringentelement and the optical rotator and including a predetermined power.114. The exposure apparatus according to claim 113, wherein the opticalsystem includes an illumination optical system which illuminates thepredetermined pattern surface.
 115. The exposure apparatus according toclaim 114, wherein the birefringent element is located near thepredetermined pattern surface, or at or near a position opticallyconjugate with the predetermined pattern surface, in an optical path ofthe illumination optical system, and wherein the optical memberincluding the predetermined power includes an imaging optical systemwhich establishes the position optically conjugate with thepredetermined pattern surface.
 116. The exposure apparatus according toclaim 115, wherein the birefringent element is located at or near theposition optically conjugate with the predetermined pattern surface, inthe optical path of the illumination optical system, and wherein theoptical rotator is located in the imaging optical system in theillumination optical system.
 117. The exposure apparatus according toclaim 115, wherein the illumination optical system forms a secondarylight source including a predetermined optical intensity distribution,on an illumination pupil surface, and wherein the predetermined opticalintensity distribution of the secondary light source is so set that anoptical intensity in a pupil center region being a region on theillumination pupil and including an optical axis is smaller than anoptical intensity in a region around the pupil center region.
 118. Theexposure apparatus according to claim 117, wherein the predeterminedoptical intensity distribution of the secondary light source includes anoptical intensity distribution of an annular shape or multi-pole shape.119. The exposure apparatus according to claim 114, wherein the opticalsystem includes a projection optical system which forms an image of thepredetermined pattern on a surface of the photosensitive substratethrough a liquid.
 120. A device fabrication method comprising: preparinga photosensitive substrate; and exposing a pattern to be transferred, onthe photosensitive substrate through an optical system; wherein saidoptical system comprises a birefringent element and an optical rotator,wherein the exposing comprises: achieving a substantiallycircumferential distribution or a substantially radial distribution as afast axis distribution in a lens aperture by the birefringent element;and rotating a polarization state in the lens aperture being apolarization state of a beam bundle including passed through thebirefringent element, by the optical rotator.
 121. The devicefabrication method according to claim 120, wherein the optical systemincludes an illumination optical system, and wherein the exposingincludes illuminating the predetermined pattern in a substantiallytelecentric manner through the optical system.
 122. The devicefabrication method according to claim 121, wherein the birefringentelement is located at or near a position optically conjugate with thepredetermined pattern surface, in an optical path of the illuminationoptical system.
 123. The device fabrication method according to claim121, wherein the illuminating comprises forming a secondary light sourceincluding a predetermined optical intensity distribution, on anillumination pupil plane, and wherein the predetermined opticalintensity distribution of the secondary light source is so set that anoptical intensity in a pupil center region being a region on theillumination pupil and including an optical axis is smaller than anoptical intensity in a region around the pupil center region.
 124. Thedevice fabrication method according to claim 123, wherein thepredetermined optical intensity distribution of the secondary lightsource includes an optical intensity distribution of an annular shape ormulti-pole shape.
 125. The device fabrication method according to claim120, wherein the optical system includes an illumination optical systemand a projection optical system, and wherein the exposing includesilluminating the predetermined pattern surface in a substantiallytelecentric manner by the illumination optical system, and forming animage of the predetermined pattern surface on a surface of thephotosensitive substrate by the projection optical system.
 126. Thedevice fabrication method according to claim 125, wherein thebirefringent element is located in an optical path of the illuminationoptical system, and wherein the optical rotator is located in an opticalpath of the projection optical system.
 127. The device fabricationmethod according to claim 126, wherein the birefringent element islocated near the predetermined pattern surface, or at or near a positionoptically conjugate with the predetermined pattern surface, in theoptical path of the illumination optical system.
 128. The devicefabrication method according to claim 120, wherein the optical systemincludes a projection optical system, and wherein the exposing includesforming an image of the predetermined pattern on a surface of thephotosensitive substrate through a liquid.
 129. A device fabricationmethod comprising: preparing a photosensitive substrate; and exposing apattern to be transferred, on the photosensitive substrate through anoptical system; wherein the optical system comprises a birefringentoptical rotator which is made of an optical material with linearbirefringence and optical rotatory power and an optic axis of which isarranged substantially in parallel with an optical axis of the opticalsystem, and wherein the exposing comprises making a beam bundle in asubstantially circular polarization state incident to the birefringentoptical rotator.
 130. The device fabrication method according to claim129, wherein the making the beam bundle in the substantially circularpolarization state incident to the birefringent optical rotatorcomprises making a beam bundle of substantially spherical waves incidentto the birefringent optical rotator, and wherein the exposing comprisesconverting a beam bundle in a peripheral region of the beam bundleincident to the birefringent optical rotator, into a beam bundle in asubstantially linear polarization state of substantially circumferentialvibration in a lens aperture.
 131. The device fabrication methodaccording to claim 129, wherein the optical system includes anillumination optical system, and wherein the exposing includesilluminating the predetermined pattern in a substantially telecentricmanner through the optical system.
 132. The device fabrication methodaccording to claim 131, wherein the birefringent optical rotator islocated near the predetermined pattern surface, or at or near a positionoptically conjugate with the predetermined pattern surface, in anoptical path of the illumination optical system.
 133. The devicefabrication method according to claim 132, wherein the illuminatingcomprises forming step of forming a secondary light source including apredetermined optical intensity distribution, on an illumination pupilplane, and wherein the predetermined optical intensity distribution ofthe secondary light source is so set that an optical intensity in apupil center region being a region on the illumination pupil andincluding an optical axis is smaller than an optical intensity in aregion around the pupil center region.
 134. The device fabricationmethod according to claim 133, wherein the predetermined opticalintensity distribution of the secondary light source includes an opticalintensity distribution of an annular shape or multi-pole shape.
 135. Thedevice fabrication method according to claim 129, wherein the opticalsystem includes a projection optical system, and wherein the exposingincludes forming an image of the predetermined pattern on a surface ofthe photosensitive substrate by the projection optical system.
 136. Thedevice fabrication method according to claim 135, wherein the projectionoptical system is arranged to be substantially telecentric on thepredetermined pattern surface side, and wherein the birefringent opticalrotator is located in an optical path which is substantially telecentricon the predetermined pattern surface side.
 137. The device fabricationmethod according to claim 135, wherein the projection optical system isarranged to be substantially telecentric on the photosensitive substratesurface side, and wherein the birefringent optical rotator is located inan optical path which is substantially telecentric on the photosensitivesubstrate surface side.
 138. The device fabrication method according toclaim 135, wherein the forming the image of the predetermined patternincludes forming the image of the predetermined pattern on the surfaceof the photosensitive substrate through a liquid.
 139. A devicefabrication method comprising: preparing a photosensitive substrate; andexposing a pattern to be transferred, on the photosensitive substratethrough an optical system; wherein the optical system comprises abirefringent element, an optical rotator, and an optical memberincluding a predetermined power, and wherein the exposing comprisesmaking a beam bundle including passed through the birefringent element,pass in order through the optical member including the predeterminedpower and through the optical rotator.
 140. The device fabricationmethod according to claim 139, wherein the optical system includes anillumination optical system, and wherein the exposing includes anillumination step for illuminating the predetermined pattern through theoptical system.
 141. The device fabrication method according to claim140, wherein the birefringent element is located near the predeterminedpattern surface, or at or near a position optically conjugate with thepredetermined pattern surface, in an optical path of the illuminationoptical system, and wherein the illuminating includes establishing theposition optically conjugate with the predetermined pattern surface, bythe optical member including the predetermined power.
 142. The devicefabrication method according to claim 141, wherein the birefringentelement is located at or near the position optically conjugate with thepredetermined pattern surface, in the optical path of the illuminationoptical system, and wherein the establishing the position opticallyconjugate with the predetermined pattern surface comprises making a beambundle pass through the optical rotator.
 143. The device fabricationmethod according to claim 141, wherein the illuminating comprisesforming a secondary light source including a predetermined opticalintensity distribution, on an illumination pupil plane, and wherein thepredetermined optical intensity distribution of the secondary lightsource is so set that an optical intensity in a pupil center regionbeing a region on the illumination pupil and including an optical axisis smaller than an optical intensity in a region around the pupil centerregion.
 144. The device fabrication method according to claim 143,wherein the predetermined optical intensity distribution of thesecondary light source includes an optical intensity distribution of anannular shape or multi-pole shape.
 145. The device fabrication methodaccording to claim 141, wherein the birefringent element is located ator near the position optically conjugate with the predetermined patternsurface, in the optical path of the illumination optical system, whereinthe illuminating comprises guiding a beam bundle from an opticalintegrator to the predetermined pattern surface, and wherein the beambundle including passed through the optical integrator is incident tothe optical rotator.
 146. The device fabrication method according toclaim 139, wherein the optical system includes a projection opticalsystem, and wherein the exposing includes forming an image of thepredetermined pattern on a surface of the photosensitive substratethrough a liquid.